The data structure of the operation result of MySQL database
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I. data structure of database operation results
Struct zbx_db_result
{
# if defined (HAVE_IBM_DB2)
SQLHANDLE hstmt
SQLSMALLINT nalloc
SQLSMALLINT ncolumn
DB_ROW values
DB_ROW values_cli
SQLINTEGER * values_len
# elif defined (HAVE_MYSQL)
MYSQL_RES * result
# elif defined (HAVE_ORACLE)
OCIStmt * stmthp; / * the statement handle for select operations * /
Int ncolumn
DB_ROW values
Ub4 * values_alloc
OCILobLocator * * clobs
# elif defined (HAVE_POSTGRESQL)
PGresult * pg_result
Int row_num
Int fld_num
Int cursor
DB_ROW values
# elif defined (HAVE_SQLITE3)
Int curow
Char * * data
Int nrow
Int ncolumn
DB_ROW values
# endif
}
The database is queried according to sql
/ *
* *
* Function: DBselect *
* *
* Purpose: execute a select statement *
* *
* Comments: retry until DB is up *
* *
* * /
DB_RESULT _ _ zbx_DBselect (const char * fmt,...)
{
Va_list args; / / Parameter list
DB_RESULT rc
Va_start (args, fmt)
Rc = zbx_db_vselect (fmt, args)
While ((DB_RESULT) ZBX_DB_DOWN = = rc)
{
DBclose ()
DBconnect (ZBX_DB_CONNECT_NORMAL)
If ((DB_RESULT) ZBX_DB_DOWN = (rc = zbx_db_vselect (fmt, args)
{
Zabbix_log (LOG_LEVEL_ERR, "database is down: retrying in% d seconds", ZBX_DB_WAIT_DOWN)
Connection_failure = 1
Sleep (ZBX_DB_WAIT_DOWN)
}
}
Va_end (args)
Return rc
}
3. Data structure of MySQL operation result
Typedef struct st_mysql_res {
My_ulonglong row_count
MYSQL_FIELD * fields
MYSQL_DATA * data
MYSQL_ROWS * data_cursor
Unsigned long * lengths; / * column lengths of current row * /
MYSQL * handle; / * for unbuffered reads * /
Const struct st_mysql_methods * methods
MYSQL_ROW row; / * If unbuffered read * /
MYSQL_ROW current_row; / * buffer to current row * /
MEM_ROOT field_alloc
Unsigned int field_count, current_field
My_bool eof; / * Used by mysql_fetch_row * /
/ * mysql_stmt_close () had to cancel this result * /
My_bool unbuffered_fetch_cancelled
Void * extension
} MYSQL_RES
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