如何确定字段在SQL Server 2008 R2中是否具有前导零？

Question

I have a varchar field on a table and I need to know if there is a way to know if it starts with a given number of zeroes.

Do I have to use variables or if-else?

Answer 1

You can use LEFT to get leading text and compare with zeros string:

DECLARE @number INT = 3;

SELECT *
FROM your_table
WHERE LEFT(column_name, @number) = REPLICATE('0', @number)
-- AND SUBSTRING(col, @number+1,1) <> '0'; If you need exact number of leading zeros

LiveDemo

Or when you need a flag:

SELECT *,
  [has_3_leading_zeros] = CASE 
                            WHEN LEFT(column_name, @number) = REPLICATE('0', @number) 
                            THEN 1 ELSE 0 END
FROM your_table;

LiveDemo2

Another way is to use LIKE (this solution is SARG-able and should have better performance if column has index):

SELECT *
FROM your_table
WHERE col LIKE REPLICATE('0', @number) + '%'