Delphi. 11



         

IS NULL


SQL- NULL , . , NULL, unknown (, , ), true false, ..

WHERE dept_no = NULL

WHERE NULL = NULL.

IS NULL true , IS NULL null (, ). IS NOT NULL, , - .

SELECT department, mngr_no

FROM department

WHERE mngr_no IS NULL ,

DEPARTMENT MNGR_NO

========================= =======

Marketing <null>

Software Products Div. <null>

Software Development <null>

Field Office: Singapore <null>

EXIST, ANY, ALL, SOME, SINGULAR , .