Dynamic SQL and loop challenge, SQL Server 2012 - sql

Question

I have n tables that is unknown before runtime with tablename always being tablename1, tablename2... tablenameN. The first column of each table is always Name. The challenge is to change that column name in each table to Name1, Name2.. NameN. I know I should be using sp_rename and a loop. Having trouble building up the query, I'm pretty new to SQL. Help would be appreciated. THanks

Answer 1

This should do the rename:
DECLARE #counter INT;
DECLARE #tableName NVARCHAR(100);
DECLARE #columnName NVARCHAR(100);
DECLARE #newColumnName NVARCHAR(100);
SET #counter = 1;
WHILE #counter < 65536
BEGIN
SET #tableName = 'tableName' + CAST(#counter AS NVARCHAR)
IF EXISTS(SELECT * FROM sys.tables WHERE name = #tableName)
BEGIN
SET #columnName = #tableName + N'.name';
SET #newColumnName = N'name' + CAST(#counter AS NVARCHAR);
EXEC sp_rename #objname=#columnName, #newName=#newColumnName;
END
ELSE
BEGIN
SET #counter = 65536
END
SET #counter = #counter + 1
END
It's a bit crude though.. and renames only 65535 tables and full amount only when there's none missing in between.

Answer 2

Uncomment sql_exec when you're sure it does what you're expecting :)
DECLARE #TableName sysname, #ColName sysname
DECLARE #num sysname
DECLARE #sql nvarchar(4000)
DECLARE cTables CURSOR FOR SELECT name from dbo.sysobjects where Category = 0 AND type NOT IN (N'F', N'FN', N'IF', N'TF', N'P', N'TR', N'V', N'K') AND name like 'tablename%'
OPEN cTables
FETCH NEXT FROM cTables INTO #TableName
WHILE ##FETCH_STATUS = 0
BEGIN
SET #num = SUBSTRING(#Tablename, 10, 5)
SET #sql = N'sp_RENAME ''' + #TableName + '.[Name]'' , ''[Name' + #num + ']'', ''COLUMN'''
PRINT #sql
-- EXEC sp_sqlexec #sql
FETCH NEXT FROM cTables INTO #TableName
END
CLOSE cTables;
DEALLOCATE cTables;

Answer 3

Here's a SP - give it a try ;-)
CREATE PROCEDURE dbo.Rename
(
#n INT
)
AS
BEGIN
SET NOCOUNT ON
DECLARE #Stmt NVARCHAR(MAX)
DECLARE #i INT
DECLARE #tabname NVARCHAR(MAX)
DECLARE #colname NVARCHAR(MAX)
SET #i = 1
WHILE #i <= #n
BEGIN
SET #tabname = N'tablename' + CAST(#i AS NVARCHAR(MAX))
SET #colname = N'name' + CAST(#i AS NVARCHAR(MAX))
IF EXISTS(SELECT TOP 1 1 FROM sys.tables t WHERE t.name = #tabname)
BEGIN
SET #Stmt = N'EXEC sp_rename ''' + #tabname + '.[name]'', ''' + #colname +''',''COLUMN'''
--PRINT #Stmt
EXEC sp_executesql #Stmt
END
SET #i = #i + 1
END
END