Rules for Better SQL Programming # Tip 1
Always try to keep the hit list small by using the where clause were ever required or by describing the full search condition in the where clause.
Select Query #1
Wrong
SELECT * FROM sflight INTO xflight. CHECK xflight-carrid = 'LH '. CHECK xflight-connid = '0300'. CHECK xflight-fldate(4) = '2002'. WRITE: / xflight-fldate. ENDSELECT. |
Right
SELECT * FROM sflight INTO xflight WHERE carrid = 'LH ' AND connid = '0300' AND fldate LIKE '2002%'. WRITE: / xflight-fldate. ENDSELECT. |
Select Query #2
Wrong
SELECT * FROM sflight INTO xflight WHERE carrid = 'LH ' AND connid = '0300'. CHECK xflight-fldate(4) = '2002'. WRITE: / xflight-fldate. ENDSELECT. |
Right
SELECT * FROM sflight INTO xflight WHERE carrid = 'LH ' AND connid = '0300' AND fldate LIKE '2002%'. WRITE: / xflight-fldate. ENDSELECT. |
