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More comments in prepared statements code.
libmysql/libmysql.c: Extended comments for mysql_stmt_init, mysql_stmt_prepare, mysql_stmt_result_metadata. Few bits of code moved around and cleaned up. sql/sql_prepare.cc: Commented case with ulonglong length in get_param_length
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2 changed files with 161 additions and 80 deletions
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@ -1640,70 +1640,46 @@ myodbc_remove_escape(MYSQL *mysql,char *name)
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}
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/********************************************************************
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Implementation of new client API for 4.1 version.
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Implementation of new client-server prototypes for 4.1 version
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starts from here ..
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mysql_* are real prototypes used by applications
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mysql_stmt_* are real prototypes used by applications.
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To make API work in embedded library all functions performing
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real I/O are prefixed with 'cli_' (abbreviated from 'Call Level
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Interface'). This functions are invoked via pointers set in
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MYSQL::methods structure. Embedded counterparts, prefixed with
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'emb_' reside in libmysqld/lib_sql.cc.
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*********************************************************************/
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/********************************************************************
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Misc Utility functions
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********************************************************************/
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/*
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Set the internal stmt error messages
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*/
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static void set_stmt_error(MYSQL_STMT * stmt, int errcode,
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const char *sqlstate)
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{
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DBUG_ENTER("set_stmt_error");
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DBUG_PRINT("enter", ("error: %d '%s'", errcode, ER(errcode)));
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DBUG_ASSERT(stmt != 0);
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stmt->last_errno= errcode;
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strmov(stmt->last_error, ER(errcode));
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strmov(stmt->sqlstate, sqlstate);
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DBUG_VOID_RETURN;
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}
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/******************* Declarations ***********************************/
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/*
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Copy error message to statement handler
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These functions are called by function pointer MYSQL_STMT::read_row_func.
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Each function corresponds to one of the read methods:
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- mysql_stmt_fetch without prior mysql_stmt_store_result,
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- mysql_stmt_fetch when result is stored,
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- mysql_stmt_fetch when there are no rows (always returns MYSQL_NO_DATA)
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*/
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void set_stmt_errmsg(MYSQL_STMT * stmt, const char *err, int errcode,
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const char *sqlstate)
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{
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DBUG_ENTER("set_stmt_error_msg");
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DBUG_PRINT("enter", ("error: %d/%s '%s'", errcode, sqlstate, err));
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DBUG_ASSERT(stmt != 0);
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stmt->last_errno= errcode;
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if (err && err[0])
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strmov(stmt->last_error, err);
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strmov(stmt->sqlstate, sqlstate);
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DBUG_VOID_RETURN;
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}
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static int stmt_read_row_unbuffered(MYSQL_STMT *stmt, unsigned char **row);
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static int stmt_read_row_buffered(MYSQL_STMT *stmt, unsigned char **row);
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static int stmt_read_row_no_data(MYSQL_STMT *stmt, unsigned char **row);
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/**************** Misc utility functions ****************************/
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/*
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Reallocate the NET package to be at least of 'length' bytes
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SYNPOSIS
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my_realloc_str()
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net The NET structure to modify
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int length Ensure that net->buff is at least this big
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net The NET structure to modify
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length Ensure that net->buff is at least this big
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RETURN VALUES
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0 ok
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1 Error
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*/
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static my_bool my_realloc_str(NET *net, ulong length)
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@ -1719,20 +1695,54 @@ static my_bool my_realloc_str(NET *net, ulong length)
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DBUG_RETURN(res);
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}
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/********************************************************************
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Prepare related implementations
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********************************************************************/
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static int stmt_read_row_unbuffered(MYSQL_STMT *stmt, unsigned char **row);
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static int stmt_read_row_buffered(MYSQL_STMT *stmt, unsigned char **row);
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static int stmt_read_row_no_data(MYSQL_STMT *stmt, unsigned char **row);
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/*
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Read the prepared statement results ..
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Set statement error code, sqlstate, and error message
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from given errcode and sqlstate.
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*/
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NOTE
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This is only called for connection to servers that supports
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prepared statements (and thus the 4.1 protocol)
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static void set_stmt_error(MYSQL_STMT * stmt, int errcode,
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const char *sqlstate)
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{
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DBUG_ENTER("set_stmt_error");
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DBUG_PRINT("enter", ("error: %d '%s'", errcode, ER(errcode)));
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DBUG_ASSERT(stmt != 0);
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stmt->last_errno= errcode;
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strmov(stmt->last_error, ER(errcode));
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strmov(stmt->sqlstate, sqlstate);
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DBUG_VOID_RETURN;
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}
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/*
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Set statement error code, sqlstate, and error message.
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*/
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void set_stmt_errmsg(MYSQL_STMT * stmt, const char *err, int errcode,
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const char *sqlstate)
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{
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DBUG_ENTER("set_stmt_errmsg");
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DBUG_PRINT("enter", ("error: %d/%s '%s'", errcode, sqlstate, err));
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DBUG_ASSERT(stmt != 0);
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stmt->last_errno= errcode;
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if (err && err[0])
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strmov(stmt->last_error, err);
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strmov(stmt->sqlstate, sqlstate);
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DBUG_VOID_RETURN;
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}
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/*
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Read and unpack server reply to COM_PREPARE command (sent from
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mysql_stmt_prepare).
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SYNOPSIS
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cli_read_prepare_result()
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mysql connection handle
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stmt statement handle
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RETURN VALUES
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0 ok
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@ -1752,7 +1762,9 @@ my_bool cli_read_prepare_result(MYSQL *mysql, MYSQL_STMT *stmt)
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pos= (uchar*) mysql->net.read_pos;
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stmt->stmt_id= uint4korr(pos+1); pos+= 5;
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/* Number of columns in result set */
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field_count= uint2korr(pos); pos+= 2;
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/* Number of placeholders in the statement */
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param_count= uint2korr(pos); pos+= 2;
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if (param_count != 0)
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@ -1802,10 +1814,30 @@ MYSQL_STMT * STDCALL mysql_prepare(MYSQL *mysql, const char *query,
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#endif
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/*
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Allocate memory and init prepared statement structure
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Allocate memory and init prepared statement structure.
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SYNOPSIS
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mysql_stmt_init()
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mysql connection handle
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mysql connection handle
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DESCRIPTION
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This is an entry point of the new API. Returned handle stands for
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a server-side prepared statement. Memory for this structure (~700
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bytes) is allocated using 'malloc'. Once created, the handle can be
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reused many times. Created statement handle is bound to connection
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handle provided to this call: it's lifetime is limited by lifetime
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of connection.
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'mysql_stmt_init()' is a pure local call, server side structure is
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created only in mysql_stmt_prepare.
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Next steps you may want to make:
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- set a statement attribute (mysql_stmt_attr_set()),
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- prepare statement handle with a query (mysql_stmt_prepare()),
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- close statement handle and free it's memory (mysql_stmt_close()),
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- reset statement with mysql_stmt_reset() (a no-op which will
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just return).
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Behaviour of the rest of API calls on this statement is not defined yet
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(though we're working on making each wrong call sequence return
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error).
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RETURN VALUE
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statement structure upon success and NULL if out of
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@ -1838,27 +1870,41 @@ mysql_stmt_init(MYSQL *mysql)
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DBUG_RETURN(stmt);
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}
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/*
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Prepare server side statement with query:
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Prepare server side statement with query.
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SYNOPSIS
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mysql_stmt_prepare()
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query statement to prepare
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length statement length
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stmt statement handle
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query statement to prepare
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length statement length
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DESCRIPTION
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- if this is a re-prepare of the statement, first close previous data
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Associate statement with statement handle. This is done both on
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client and server sides. At this point the server parses given query
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and creates an internal structure to represent it.
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Next steps you may want to make:
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- find out if this statement returns a result set by
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calling mysql_stmt_field_count(), and get result set metadata
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with mysql_stmt_result_metadata(),
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- if query contains placeholders, bind input parameters to placeholders
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using mysql_stmt_bind_param(),
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- otherwise proceed directly to mysql_stmt_execute().
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IMPLEMENTATION NOTES
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- if this is a re-prepare of the statement, first close previous data
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structure on the server and free old statement data
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- send the query to server and get back number of placeholders,
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- then send the query to server and get back number of placeholders,
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number of columns in result set (if any), and result set metadata.
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At the same time allocate memory for input and output parameters
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At the same time allocate memory for input and output parameters
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to have less checks in mysql_stmt_bind_{param, result}.
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RETURN VALUES
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0 success
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!0 error
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!0 error
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*/
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int STDCALL
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mysql_stmt_prepare(MYSQL_STMT *stmt, const char *query, ulong length)
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{
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@ -1938,8 +1984,10 @@ mysql_stmt_prepare(MYSQL_STMT *stmt, const char *query, ulong length)
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}
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/*
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Get the execute query meta information for non-select
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statements.
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Get result set metadata from reply to mysql_stmt_execute.
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This is used mainly for SHOW commands, as metadata for these
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commands is sent only with result set.
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To be removed when all commands will fully support prepared mode.
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*/
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static unsigned int alloc_stmt_fields(MYSQL_STMT *stmt)
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@ -1983,8 +2031,31 @@ static unsigned int alloc_stmt_fields(MYSQL_STMT *stmt)
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}
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/*
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Returns prepared meta information in the form of resultset
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to client.
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Returns prepared statement metadata in the form of a result set.
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SYNOPSIS
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mysql_stmt_result_metadata()
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stmt statement handle
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RETURN
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NULL statement contains no result set or out of memory.
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In the latter case you can retreive error message
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with mysql_stmt_error.
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MYSQL_RES a result set with no rows
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DESCRIPTION
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This function should be used after mysql_stmt_execute().
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You can safely check that prepared statement has a result set by calling
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mysql_stmt_num_fields(): if number of fields is not zero, you can call
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this function to get fields metadata.
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Next steps you may want to make:
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- find out number of columns in result set by calling
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mysql_num_fields(res) (the same value is returned by
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mysql_stmt_num_fields)
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- fetch metadata for any column with mysql_fetch_field,
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mysql_fetch_field_direct, mysql_fetch_fields, mysql_field_seek.
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- free returned MYSQL_RES structure with mysql_free_result.
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- proceed to binding of output parameters.
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*/
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MYSQL_RES * STDCALL
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@ -2016,8 +2087,9 @@ mysql_stmt_result_metadata(MYSQL_STMT *stmt)
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}
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/*
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Returns parameter columns meta information in the form of
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resultset.
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Returns parameter columns meta information in the form of
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result set.
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XXX: not implemented yet.
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*/
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MYSQL_RES * STDCALL
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@ -2036,12 +2108,8 @@ mysql_stmt_param_metadata(MYSQL_STMT *stmt)
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}
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/********************************************************************
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Prepare-execute, and param handling
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*********************************************************************/
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/****************************************************************************
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Functions to store parameter data from a prepared statement.
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/*
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Functions to store parameter data in network packet.
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All functions have the following characteristics:
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@ -2053,7 +2121,7 @@ mysql_stmt_param_metadata(MYSQL_STMT *stmt)
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RETURN VALUES
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0 ok
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1 Error (Can't alloc net->buffer)
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****************************************************************************/
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*/
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static void store_param_tinyint(NET *net, MYSQL_BIND *param)
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{
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@ -2162,7 +2230,8 @@ static void store_param_datetime(NET *net, MYSQL_BIND *param)
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static void store_param_str(NET *net, MYSQL_BIND *param)
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{
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ulong length= param->length ? *param->length : param->buffer_length;
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/* param->length is always set in mysql_stmt_bind_param */
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ulong length= *param->length;
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char *to= (char *) net_store_length((char *) net->write_pos, length);
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memcpy(to, param->buffer, length);
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net->write_pos= (uchar*) to+length;
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@ -2538,6 +2607,7 @@ my_ulonglong STDCALL mysql_stmt_insert_id(MYSQL_STMT *stmt)
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return stmt->insert_id;
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}
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static my_bool int_is_null_true= 1; /* Used for MYSQL_TYPE_NULL */
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static my_bool int_is_null_false= 0;
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@ -2630,6 +2700,11 @@ my_bool STDCALL mysql_stmt_bind_param(MYSQL_STMT *stmt, MYSQL_BIND * bind)
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case MYSQL_TYPE_VAR_STRING:
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case MYSQL_TYPE_STRING:
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param->store_param_func= store_param_str;
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/*
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For variable length types we expect user to set
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length or buffer_length. Otherwise mysql_stmt_execute
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will just fail.
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*/
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break;
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default:
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strmov(stmt->sqlstate, unknown_sqlstate);
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@ -2671,7 +2746,6 @@ my_bool STDCALL mysql_stmt_bind_param(MYSQL_STMT *stmt, MYSQL_BIND * bind)
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1 error
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*/
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my_bool STDCALL
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mysql_stmt_send_long_data(MYSQL_STMT *stmt, uint param_number,
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const char *data, ulong length)
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@ -2769,6 +2843,7 @@ static uint read_binary_time(MYSQL_TIME *tm, uchar **pos)
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uchar *to;
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uint length;
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/* net_field_length will set pos to the first byte of data */
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if (!(length= net_field_length(pos)))
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{
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set_zero_time(tm);
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@ -210,7 +210,13 @@ static ulong get_param_length(uchar **packet, ulong len)
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if (len < 5)
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return 0;
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(*packet)+=9; // Must be 254 when here
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/* TODO: why uint4korr here? (should be uint8korr) */
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/*
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In our client-server protocol all numbers bigger than 2^24
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stored as 8 bytes with uint8korr. Here we always know that
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parameter length is less than 2^4 so don't look at the second
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4 bytes. But still we need to obey the protocol hence 9 in the
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assignment above.
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*/
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return (ulong) uint4korr(pos+1);
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}
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#else
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