=5 , 30 NULL- .
UPDATE
SET = '', = (+30), = NULL
WHERE = 5;
( - = 17).
UPDATE
SET = * 3
WHERE <> 17;
_ .
UPDATE
SET = 0, _ = 0
WHERE IN
(SELECT
FROM
WHERE IN ('', ''));
= 13 = 20.
UPDATE UPDATE
SET = 20 SET = 20
WHERE = 13; WHERE = 13;
UPDATE UPDATE
SET = 20 SET = 20
WHERE = 13; WHERE = 13;
, , . ( ), , . .
4.5.
, SELECT, DELETE, INSERT UPDATE. , :
1. WHERE DELETE UPDATE , FROM , ( ) . , INSERT , .
, SQL
INSERT
INTO
SELECT (33), ,
FROM
WHERE = 17;
, , 33- , , , 17- . - , , :
DELETE
FROM ;
INSERT
INTO (, , )
SELECT (33), ,
FROM
WHERE = 17;
INSERT
INTO
SELECT , ,
FROM ;
2. , . [2].
5.
- , , : , , , , , .. , SQL, , .
|
|
|
, SYSTABLES . , , , . SYSCOLUMNS , , , , .
SELECT . , , , ( ):
SELRCT Tab_name,N_col,N_row,Tab_owner,Comments
FROM SYSTABLES;
, . 5.1,.
SELECT Col_name, Type, Length, Comments
FROM SYSCOLUMNS
WHERE Tab_name = '';
, . 5.1,.
)
| Tab_name | N_col | N_row | Tab_owner | Comments |
| ... | ||||
| SYS_TABLES | SYSTEM | |||
| SYS_COLUMNS | SYSTEM | |||
| ... | ||||
| KIRILLOW | , - | |||
| GROMOW | ||||
| _ | KIRILLOW | |||
| GROMOW | ||||
| KIRILLOW | ||||
| KIRILLOW | ||||
| ... |
)
| Col_name | Type | Length | Comments |
| INTEGER | |||
| TEXT | |||
| TEXT | (, ,...) | ||
| TEXT | |||
| REAL | |||
| INTEGER | () |
. 5.1.
, , . SQL .
, DELETE, INSERT UPDATE. , , , .. , .
5.2.
SQL CREATE TABLE ( ), . :
CREATE TABLE _ ( _ [NOT NULL]
[, _ [NOT NULL]]...);
_ , (, , .1.2).
,
CREATE TABLE
( SMALLINT NOT NULL,
CHAR (70) NOT NULL,
|
|
|
CHAR (1),
CHAR (10),
FLOAT,
SMALLINT);
, , . , , CREATE TABLE. Kirillov, Kirillov. Kirillov. , .
NOT NULL , .. , " " " ". , () _ (, , () ).
DROP TABLE ( ):
DROP TABLE _;
, , , (. . 5.3).
SQL ALTER TABLE ( ), , .. . " ", , .
5.3.
. - , . , (, ). , , , :
| , | ||||||||
, ( ) , SELECT, DELETE, INSERT UPDATE. SQL . , - , , - , , .. , ( , , ).
, - , (). , , . - . , , , , (, : , , ).
|
|
|
SQL CREATE INDEX ( ),
CREATE [UNIQUE] INDEX _ ON _
( [[ASC] | DESC] [, [[ASC] | DESC]]...);
UNIQUE () , ( ) .
,
CREATE UNIQUE INDEX _ ON ();
CREATE INDEX _ ON ();
( ) -
CREATE UNIQUE INDEX __ ON (, );
( 1000 ) , , - - .
, , ?
, . , , - . - () - , ( ) -. , DROP INDEX ( ), :
DROP INDEX _;
, , WHERE ORDER BY , .
5.4.
