SQL

declare variables sql

--      name         type               value
DECLARE @PersonId AS UNIQUEIDENTIFIER = 'ddb7bfff-9ce8-4651-6973-08d9a46c90b6'

sql declare table variable

DECLARE @TABLE TABLE( COL1 INT, COL2 VARCHAR(30))

sql declare variable

DECLARE @datecurrent datetime2
set @datecurrent = CAST(getdate() AS smalldatetime)

declare value in sql

DECLARE  { @LOCAL_VARIABLE[AS] data_type  [ = value ] } 

declare table variable sql

DECLARE @TableVariable TABLE (Id INT)

INSERT INTO @TableVariable
SELECT Id
FROM TableName
WHERE....

SELECT *
FROM TableName
WHERE Id IN ( SELECT Id FROM @TableVariable)

how to declare a variable in sql

DECLARE @COURSE_ID AS INT, @COURSE_NAME VARCHAR (10);