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DESC command is used to obtain the metadata information of the table, including field name, data type, whether it is empty, default value, primary key and foreign key, etc. It returns a table containing Field, Type, Null, Key, Default, Extra and other columns, displaying the field information and constraints of the table.
DESC command in MySQL
The DESC command is an important tool in the MySQL database for obtaining field information in the table. tool. The syntax format is:
<code class="SQL">DESC <表名>;</code>
Usage
The DESC command obtains the metadata information of the specified table, including field name, data type, whether it is empty, default value, and primary key and foreign keys etc. The return result is a table containing the following columns:
Detailed explanation
Example
The following example queries the field information of the table named "employees":
<code class="SQL">DESC employees;</code>
The results may be as follows:
<code>+-------+--------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+--------+------+-----+---------+-------+ | id | int(11) | NO | PRI | NULL | | | name | varchar(255) | YES | | NULL | | | email | varchar(255) | YES | | NULL | | | phone | int(11) | YES | | NULL | | +-------+--------+------+-----+---------+-------+</code>
Conclusion
The DESC command is an important tool for obtaining field information in a table and can be used to understand the structure and constraints of the table. It is very useful in database design, debugging and optimization.
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