Using a Cursor to Update Rows in Single Table

问题

I am seeking guidance using MS SQL cursor or SQL while loop to merge (add, update, and set inactive) rows using single table based on criteria below resulting in seeking the final dataset:

TABLE VIEW (SELECT * FROM TABLE WHERE ENTITY = 123 (@ID)

ENTITY ENTITY_TYPE VALUE STATUS_TYPE

123    1     1     1
123    1    4     1
123    1     9     1

TABLE VIEW (SELECT * FROM TABLE WHERE ENTITY = 456 (@OverrideID)

ENTITY    ENTITY_TYPE    VALUE    STATUS_TYPE
456     1    1    1
456    1    5    1

Final Data Set below:

ENTITY&nbsp&nbsp&nbspTYPE VALUE STATUS_TYPE

123     1     1     3
123     1     4     3
123     1     9     3
456     1     1     1
456     1     4     1
456     1     9     1
456     1     1     1
456     1     5    1

-- Check and compare each row
-- IF @OverrideID = @ID (MATCH)
----- Set @ID to inactive keeping copy
-- If @OverrideID != @ID (NOT MATCH)
----- Insert @ID data with @OverrideID (COPY)
----- Set @ID to inactive.

I began writing the following and need help. For reference, @ID = 123 and @OverrideID = 456

DECLARE @ENTITY BIGINT, @ENTITY_TYPE BIGINT, @VALUE BIGINT, @E1 BIGINT, @T1 BIGINT, @V1 BIGINT
DECLARE type_cursor CURSOR LOCAL FAST_FORWARD FOR
SELECT * FROM TypeValue WHERE ENTITY = @ID

SET NOCOUNT OFF
OPEN type_cursor

FETCH NEXT FROM type_cursor INTO @OverrideID, @ID, @ENTITY, @ENTITY_TYPE, @VALUE

WHILE (@@FETCH_STATUS = 0)
    BEGIN

        SELECT @ENTITY, @ENTITY_TYPE, @VALUE

     IF @VALUE IS NOT NULL
        BEGIN
        SELECT @T1 = @ENTITY_TYPE, @V1 = @VALUE
        END
    ELSE
    BEGIN
    UPDATE TypeValue
    SET ENTITY = @OverrideID, ENTITY_TYPE = @T1, VALUE = @V1 WHERE ENTITY = @ID
    END

FETCH NEXT FROM type_cursor INTO @OverrideID, @ID, @ENTITY, @ENTITY_TYPE, @VALUE

END

CLOSE type_cursor 
DEALLOCATE type_cursor 
SET NOCOUNT OFF

回答1:

That final result set looks like

    select entity,entity_type,value,3 status_type
      from [table]
     where entity = @id
 union all
    select @override,entity_type,value,status_type
      from [table]
     where entity = @id
 union all
    select entity,entity_type,value,status_type
      from [table]
     where entity = @override

来源：https://stackoverflow.com/questions/12849883/using-a-cursor-to-update-rows-in-single-table

标签

sql

sql-server

stored-procedures

merge

cursor