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

Declare a name. For an integer variable of

@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

After the variable is declared, you can use the

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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