SQL Server中存储过程中的数据长度验证

Question

I have 4 tables called A, B, C, D. These 4 tables have 10,20,30,40 columns. But these 4 tables are have 5 common columns with the same datatype and different lengths.

My action to be done is, I send a table of values (single row which has the values of those 5 common values also) to stored procedure.

Now I want to insert the row into a table which should be found by the table name (table name is available in the row itself). And there before I need to do data length validation.

It should not be like

if(len(@value1) > 800)

I need some different way to produce the length validation. Because in future, I may change the length of the column for some purpose. At the time I cannot change the value in the stored procedure. Please give me the solution

Answer 1

You can use INFORMATION_SCHEMA.COLUMNS view to fetch information of the column belonging to the table .

DECLARE @ColumnLength INT

SELECT @ColumnLength  = CHARACTER_MAXIMUM_LENGTH FROM INFORMATION_SCHEMA.COLUMNS 
WHERE TABLE_NAME = 'YourTableName' AND COLUMN_NAME='columnName'

-- Use the variable @ColumnLength for conditons in your stored proc so need of hardcoding length

IF LEN(@value1) > @ColumnLength 
BEGIN

 -- Your statements
END