# mysql\_select\_db

## Syntax

```c
int mysql_select_db(MYSQL * mysql,
                    const char * db);
```

## Parameters

* `mysql` - a mysql handle, which was previously allocated by [mysql\_init()](/docs/connectors/mariadb-connector-c/api-functions/mysql_init.md) or [mysql\_real\_connect()](/docs/connectors/mariadb-connector-c/api-functions/mysql_real_connect.md).
* `db` - the default database name

## Description

Selects a database as default. 

## Return Value

Returns zero on success, non-zero on failure.

{% hint style="info" %}
To retrieve the name of the default database either execute the SQL command `SELECT DATABASE()` or retrieve the value via [mariadb\_get\_infov()](/docs/connectors/mariadb-connector-c/api-functions/mariadb_get_infov.md) API function.

The default database can also be set by the db parameter in [mysql\_real\_connect()](/docs/connectors/mariadb-connector-c/api-functions/mysql_real_connect.md).
{% endhint %}

## Examples

### SQL

```sql
# switch to default database test
USE test;
# check default database
SELECT DATABASE();
+------------+
| database() |
+------------+
| test       |
+------------+
```

### MariadDB Connector/C

```sql
static int set_default_db(MYSQL *mysql)
{
  int rc;
  char *default_db;

  /* change default database to test */
  rc= mysql_select_db(mysql, "test");
  if (rc)
    return rc;  /* Error */

  /* get the default database */
  rc= mariadb_get_infov(mysql, MARIADB_CONNECTION_SCHEMA, &default_db);
  if (rc)
    return rc; /* Error */

  if (strcmp("test", default_db) != NULL)
  {
    printf("Wrong default database\n");
    return 1;
  }
  printf("Default database: %s", default_db);
  return 0;
}
```

## See Also

* [mysql\_real\_connect()](/docs/connectors/mariadb-connector-c/api-functions/mysql_real_connect.md)

{% @marketo/form formId="4316" %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://mariadb.com/docs/connectors/mariadb-connector-c/api-functions/mysql_select_db.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.