MS SQL (SQL Database, SQL Server), T-SQL Convention

Get Record Count

DECLARE @count INTEGER = 0;
SELECT @count = COUNT(1)
  FROM the_table;

Conditional by Record Existence

with variable

DECLARE @count INTEGER = 0;
SELECT @count = COUNT(1)
  FROM the_table;

IF @count > 0
  BEGIN
    -- some process
  END

without variable

IF EXISTS(
   SELECT 1
)
  BEGIN
    -- some process
  END

Create temporary table

Add # at the head of the table name.

CREATE TABLE #target_client (
    sample_1 VARCHAR(255),
    sample_2 VARCHAR(255)
);