What is the command for variable declaration in sql
The command for variable declaration in SQL is DECLARE, which is used to declare variables to store temporary data. Syntax: DECLARE variable_name data_type [(size)] [DEFAULT default_value]. Parameters: variable_name is the variable name, data_type is the data type, (size) specifies the maximum length for the string type, [DEFAULT default_value] is the optional default value. For example: DECLARE @age INT; declares the integer variable @age. DECLARE @name VARCHAR(5
Commands for variable declaration in SQL
In SQL, use DECLARE command to declare variables. Variables are containers for storing temporary data and can be used in queries.
<code>DECLARE variable_name data_type [(size)] [DEFAULT default_value];</code>Parameters
variable_name:
- The name of the variable.
- data_type: The data type of the variable, such as
- INT , VARCHAR
,DATE, etc.(size):For string types, specifies the maximum length of the variable. - #[DEFAULT default_value]: Optional default value, used when the variable is not assigned a value
- Example
@age:
<code>DECLARE @age INT;</code>declare a 50-length string variable named
@name and set the default value to "Unknown":
<code>DECLARE @name VARCHAR(50) DEFAULT 'Unknown';</code>
Follow-up operations
SET command to assign it
<code>SET @age = 25;</code>It can also be used. Variables used in queries:
<code>SELECT * FROM customers WHERE age > @age;</code>
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