Uable to update tables on database level

Question

I am running following query which is not working properly:
create table #temp(
tableName nvarchar(50)
insert into #temp
SELECT TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE = 'BASE TABLE'
DECLARE @name VARCHAR(50)
DECLARE @TQ VARCHAR(500)
DECLARE @ContainName VARCHAR(500)
DECLARE db_cursor CURSOR FOR
SELECT tableName
FROM #temp
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO @name
WHILE @@FETCH_STATUS = 0
BEGIN
select @name IF COL_LENGTH(@name,'IsDeleted') IS NOT NULL
begin
IF COL_LENGTH(@name,'IsActive') IS NOT NULL
begin
exec ('UPDATE '+@name+' SET [IsActive] = ~[IsDeleted]')
end
ELSE
BEGIN
exec('ALTER TABLE '+@name+' ADD IsActive bit')
exec ('UPDATE '+@name+' SET [IsActive] = ~[IsDeleted]')
exec('ALTER TABLE '+@name+' ALTER COLUMN IsActive SET DEFAULT ''true''')
END
if exists(select * from sysobjects o inner join syscolumns c on o.id = c.cdefault inner join sysobjects t on c.id = t.id where o.xtype = 'D' and c.name = 'IsDeleted' and t.name = @name)
begin
set @ContainName=(select o.name from sysobjects o inner join syscolumns c on o.id = c.cdefault inner join sysobjects t on c.id = t.id where o.xtype = 'D' and c.name = 'IsDeleted' and t.name = @name)
exec('ALTER TABLE ' + @name + ' drop constraint ' + @ContainName)
end
exec('ALTER TABLE '+@name+' DROP COLUMN [IsDeleted]')
end
FETCH NEXT FROM db_cursor INTO @name
END
CLOSE db_cursor
DEALLOCATE db_cursor
drop table #temp
In most of the tables in my db there are two columns "IsActive" and "IsDeleted" with both of them having default key constraint and of type BIT I am trying to do following:
If column IsDeleted exist, copy its negative values of IsDeleted to IsActive.
If column IsDeleted exist but not IsActive, then create column IsActive, copy negative values of IsDeleted to IsActive, then add default key constraint to the column IsDeleted.
   3.  Finally remove the default value constraint from the column IsDeleted and then drop that column.
I am running above query for each table in db.The above query is running and giving the expected result i.e. copying negative values of IsDeleted to IsActive and dropping the column IsDeleted in all the tables. Only problem is that I am getting errror: "Incorrect
syntax near the keyword 'SET'."

Answer 1

Instead of EXEC, PRINT the SQL string and check for validity:
SET NOCOUNT ON
create table #temp(
tableName nvarchar(50)
insert into #temp
SELECT TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE = 'BASE TABLE'
DECLARE @name VARCHAR(50)
DECLARE @TQ VARCHAR(500)
DECLARE @ContainName VARCHAR(500)
DECLARE db_cursor CURSOR FOR
SELECT tableName
FROM #temp
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO @name
WHILE @@FETCH_STATUS = 0
BEGIN
select @name IF COL_LENGTH(@name,'IsDeleted') IS NOT NULL
begin
IF COL_LENGTH(@name,'IsActive') IS NOT NULL
begin
PRINT CONCAT ('UPDATE '+@name+' SET [IsActive] = ~[IsDeleted]', SPACE(0))
end
ELSE
BEGIN
PRINT CONCAT ('ALTER TABLE '+@name+' ADD IsActive bit', SPACE(0))
PRINT CONCAT ('UPDATE '+@name+' SET [IsActive] = ~[IsDeleted]', SPACE(0))
PRINT CONCAT ('ALTER TABLE '+@name+' ALTER COLUMN IsActive SET DEFAULT ''true''', SPACE(0))
END
if exists(select * from sysobjects o inner join syscolumns c on o.id = c.cdefault inner join sysobjects t on c.id = t.id where o.xtype = 'D' and c.name = 'IsDeleted' and t.name = @name)
begin
set @ContainName=(select o.name from sysobjects o inner join syscolumns c on o.id = c.cdefault inner join sysobjects t on c.id = t.id where o.xtype = 'D' and c.name = 'IsDeleted' and t.name = @name)
PRINT CONCAT ('ALTER TABLE ' + @name + ' drop constraint ' + @ContainName, SPACE(0))
end
PRINT CONCAT ('ALTER TABLE '+@name+' DROP COLUMN [IsDeleted]', SPACE(0))
end
FETCH NEXT FROM db_cursor INTO @name
END
CLOSE db_cursor
DEALLOCATE db_cursor
drop table #temp
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SQL Server 2014 Database Design
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