- A MySQL 5.1 Frequently Asked Questions
- A.1 MySQL 5.1 FAQ — General
- A.2 MySQL 5.1 FAQ — Storage Engines
- A.3 MySQL 5.1 FAQ — Server SQL Mode
- A.4 MySQL 5.1 FAQ — Stored Procedures and Functions
- A.5 MySQL 5.1 FAQ — Triggers
- A.6 MySQL 5.1 FAQ — Views
- A.7 MySQL 5.1 FAQ — INFORMATION_SCHEMA
- A.8 MySQL 5.1 FAQ — Migration
- A.9 MySQL 5.1 FAQ — Security
- A.10 MySQL 5.1 FAQ — MySQL Cluster
- A.11 MySQL 5.1 FAQ — MySQL Chinese, Japanese, and Korean Character Sets
- A.12 MySQL 5.1 FAQ — Connectors & APIs
- A.13 MySQL 5.1 FAQ — Replication
- A.14 MySQL 5.1 FAQ — MySQL, DRBD, and Heartbeat
Questions
23.3.1: Is the mode dependent on the database or connection?
23.3.2: What is the default server SQL mode when My SQL 5.1 is installed?
23.3.3: Does strict mode impact performance?
23.3.4: Can the rules for strict mode be extended?
23.3.5: How do you determine the server SQL mode?
23.3.6: How many server SQL modes are there?
23.3.7: What are server SQL modes?
Questions and Answers
23.3.1: Is the mode dependent on the database or connection?
A mode is not linked to a particular database. Modes can be set
locally to the session (connection), or globally for the server.
you can change these settings using
SET [GLOBAL|SESSION]
sql_mode='.
modes'
23.3.2: What is the default server SQL mode when My SQL 5.1 is installed?
By default, no special modes are enabled. See Section 5.1.8, “Server SQL Modes”, for information about all available modes and MySQL's default behavior.
23.3.3: Does strict mode impact performance?
The intensive validation of input data that some settings requires more time than if the validation is not done. While the performance impact is not that great, if you do not require such validation (perhaps your application already handles all of this), then MySQL gives you the option of leaving strict mode disabled. However — if you do require it — strict mode can provide such validation.
23.3.4: Can the rules for strict mode be extended?
When we refer to strict mode, we mean a
mode where at least one of the modes
TRADITIONAL,
STRICT_TRANS_TABLES, or
STRICT_ALL_TABLES is enabled.
Options can be combined, so you can add additional restrictions
to a mode. See Section 5.1.8, “Server SQL Modes”, for more
information.
23.3.5: How do you determine the server SQL mode?
You can set the default SQL mode (for mysqld
startup) with the --sql-mode
option. Using the statement
SET [GLOBAL|SESSION]
sql_mode=', you can
change the settings from within a connection, either locally to
the connection, or to take effect globally. You can retrieve the
current mode by issuing a modes'SELECT @@sql_mode
statement.
23.3.6: How many server SQL modes are there?
Each mode can be independently switched on and off. See Section 5.1.8, “Server SQL Modes”, for a complete list of available modes.
23.3.7: What are server SQL modes?
Server SQL modes define what SQL syntax MySQL should support and what kind of data validation checks it should perform. This makes it easier to use MySQL in different environments and to use MySQL together with other database servers. The MySQL Server apply these modes individually to different clients. For more information, see Section 5.1.8, “Server SQL Modes”.
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