How to update primary key

Question

Here is my problem - I have 2 tables:

1. WORKER, with columns |ID|OTHER_STAF| , where ID is primary key
2. FIRM, with columns |FPK|ID|SOME

Answer 1

You could use this recursive function for generate necessary T-SQL script.

CREATE FUNCTION dbo.Update_Delete_PrimaryKey
(
    @TableName      NVARCHAR(255),
    @ColumnName     NVARCHAR(255),
    @OldValue       NVARCHAR(MAX),
    @NewValue       NVARCHAR(MAX),
    @Del            BIT
)
RETURNS NVARCHAR 
(
    MAX
)
AS
BEGIN
    DECLARE @fks TABLE 
            (
                constraint_name NVARCHAR(255),
                table_name NVARCHAR(255),
                col NVARCHAR(255)
            );
    DECLARE @Sql                  NVARCHAR(MAX),
            @EnableConstraints     NVARCHAR(MAX);

    SET @Sql = '';
    SET @EnableConstraints = '';

    INSERT INTO @fks
      (
        constraint_name,
        table_name,
        col
      )
    SELECT oConstraint.name     constraint_name,
           oParent.name         table_name,
           oParentCol.name      col
    FROM   sys.foreign_key_columns sfkc
           --INNER JOIN sys.foreign_keys sfk
           --     ON  sfk.[object_id] = sfkc.constraint_object_id

           INNER JOIN sys.sysobjects oConstraint
                ON  sfkc.constraint_object_id = oConstraint.id
           INNER JOIN sys.sysobjects oParent
                ON  sfkc.parent_object_id = oParent.id
           INNER JOIN sys.all_columns oParentCol
                ON  sfkc.parent_object_id = oParentCol.object_id
                AND sfkc.parent_column_id = oParentCol.column_id
           INNER JOIN sys.sysobjects oReference
                ON  sfkc.referenced_object_id = oReference.id
           INNER JOIN sys.all_columns oReferenceCol
                ON  sfkc.referenced_object_id = oReferenceCol.object_id
                AND sfkc.referenced_column_id = oReferenceCol.column_id
    WHERE  oReference.name = @TableName
           AND oReferenceCol.name = @ColumnName
    --AND (@Del <> 1 OR sfk.delete_referential_action = 0)
    --AND (@Del = 1 OR sfk.update_referential_action = 0)

    IF EXISTS(
           SELECT 1
           FROM   @fks
       )
    BEGIN
        DECLARE @Constraint     NVARCHAR(255),
                @Table          NVARCHAR(255),
                @Col            NVARCHAR(255)  

        DECLARE Table_Cursor CURSOR LOCAL 
        FOR
            SELECT f.constraint_name,
                   f.table_name,
                   f.col
            FROM   @fks AS f

        OPEN Table_Cursor FETCH NEXT FROM Table_Cursor INTO @Constraint, @Table,@Col  
        WHILE (@@FETCH_STATUS = 0)
        BEGIN
            IF @Del <> 1
            BEGIN
                SET @Sql = @Sql + 'ALTER TABLE ' + @Table + ' NOCHECK CONSTRAINT ' + @Constraint + CHAR(13) + CHAR(10);
                SET @EnableConstraints = @EnableConstraints + 'ALTER TABLE ' + @Table + ' CHECK CONSTRAINT ' + @Constraint 
                    + CHAR(13) + CHAR(10);
            END

            SET @Sql = @Sql + dbo.Update_Delete_PrimaryKey(@Table, @Col, @OldValue, @NewValue, @Del);
            FETCH NEXT FROM Table_Cursor INTO @Constraint, @Table,@Col
        END

        CLOSE Table_Cursor DEALLOCATE Table_Cursor
    END

    DECLARE @DataType NVARCHAR(30);
    SELECT @DataType = t.name +
           CASE 
                WHEN t.name IN ('char', 'varchar', 'nchar', 'nvarchar') THEN '(' +
                     CASE 
                          WHEN c.max_length = -1 THEN 'MAX'
                          ELSE CONVERT(
                                   VARCHAR(4),
                                   CASE 
                                        WHEN t.name IN ('nchar', 'nvarchar') THEN c.max_length / 2
                                        ELSE c.max_length
                                   END
                               )
                     END + ')'
                WHEN t.name IN ('decimal', 'numeric') THEN '(' + CONVERT(VARCHAR(4), c.precision) + ',' 
                     + CONVERT(VARCHAR(4), c.Scale) + ')'
                ELSE ''
           END
    FROM   sys.columns c
           INNER JOIN sys.types t
                ON  c.user_type_id = t.user_type_id
    WHERE  c.object_id = OBJECT_ID(@TableName)
           AND c.name = @ColumnName

    IF @Del <> 1
    BEGIN
        SET @Sql = @Sql + 'UPDATE [' + @TableName + '] SET [' + @ColumnName + '] = CONVERT(' + @DataType + ', ' + ISNULL('N''' + @NewValue + '''', 'NULL') 
            + ') WHERE [' + @ColumnName + '] = CONVERT(' + @DataType + ', ' + ISNULL('N''' + @OldValue + '''', 'NULL') +
            ');' + CHAR(13) + CHAR(10);
        SET @Sql = @Sql + @EnableConstraints;
    END
    ELSE
        SET @Sql = @Sql + 'DELETE [' + @TableName + '] WHERE [' + @ColumnName + '] = CONVERT(' + @DataType + ', N''' + @OldValue 
            + ''');' + CHAR(13) + CHAR(10);
    RETURN @Sql;
END
GO

DECLARE @Result NVARCHAR(MAX);
SET @Result = dbo.Update_Delete_PrimaryKey('@TableName', '@ColumnName', '@OldValue', '@NewValue', 0);/*Update*/
EXEC (@Result)
SET @Result = dbo.Update_Delete_PrimaryKey('@TableName', '@ColumnName', '@OldValue', NULL, 1);/*Delete*/
EXEC (@Result)
GO

DROP FUNCTION Update_Delete_PrimaryKey;