5.4.47 mysql_list_fields()

MYSQL_RES *
mysql_list_fields(MYSQL *mysql,
                  const char *table,
                  const char *wild)

Description

Note

mysql_list_fields() is deprecated and is subject to removal in a future version of MySQL. Instead, use mysql_real_query() or mysql_query() to execute a SHOW COLUMNS statement.

Returns an empty result set for which the metadata provides information about the columns in the given table that match the simple regular expression specified by the wild parameter. wild may contain the wildcard characters % or _, or may be a NULL pointer to match all fields. Calling mysql_list_fields() is similar to executing the query SHOW COLUMNS FROM tbl_name [LIKE wild].

The information obtained is roughly equivalent to that produced by executing the statement shown here using the mysql client, like this:

$> mysql test --column-type-info -e "SELECT * FROM t LIMIT 0"
Field   1:  `c1`
Catalog:    `def`
Database:   `test`
Table:      `t`
Org_table:  `t`
Type:       LONG
Collation:  binary (63)
Length:     11
Max_length: 0
Decimals:   0
Flags:      NUM 

Field   2:  `c2`
Catalog:    `def`
Database:   `test`
Table:      `t`
Org_table:  `t`
Type:       LONG
Collation:  binary (63)
Length:     11
Max_length: 0
Decimals:   0
Flags:      NUM 

$>

It is preferable to use SHOW COLUMNS FROM tbl_name instead of mysql_list_fields().

You must free the result set with mysql_free_result().

Return Values

A MYSQL_RES result set for success. NULL if an error occurred.

Errors

• CR_COMMANDS_OUT_OF_SYNC

  Commands were executed in an improper order.

• CR_SERVER_GONE_ERROR

  The MySQL server has gone away.

• CR_SERVER_LOST

  The connection to the server was lost during the query.

• CR_UNKNOWN_ERROR

  An unknown error occurred.

Example

int i;
MYSQL_RES *tbl_cols = mysql_list_fields(mysql, "mytbl", "f%");

unsigned int field_cnt = mysql_num_fields(tbl_cols);
printf("Number of columns: %d\n", field_cnt);

for (i=0; i < field_cnt; ++i)
{
  /* col describes i-th column of the table */
  MYSQL_FIELD *col = mysql_fetch_field_direct(tbl_cols, i);
  printf ("Column %d: %s\n", i, col->name);
}
mysql_free_result(tbl_cols);