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1.5.1. " ". CHARACTER AR . ;
RR[(<>)]
R[(<>)].
: , CHAR, , <>. 1 255, ., 255 . ; <>, . , <> . - .
VARCHAR, CHARACTER VARYING CHAR VARYING. , , SQL ( Oracle 2000 ). CHAR, - , , .
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, CHARACTER VARCHAR, SQL ; , '<>'
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VARCHAR [(<>)]; CHAR VARYING [(<>)]; CHARACTER VARYING[(<>)].
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CHAR VARCHAR , , , .
1.5.2. . SQL :
INTEGER - - : - -231 +231,
SMALLINT - , INTEGER, -215 +215;
DECIMAL(<>[,<>]) - ; , . ;
NUMERIC(<>[, < >]) , , , DECIMAL
FLOAT[(< >)] - ;
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DOUBLE PRECISION - -, - REAL, REAL.
Oracle NUMBER . ; ,. . :
NUMBER[(< >[, <>])]
- <> , : 38, -<> 0. <> 1 38; <> 84 128. . . , NUMBER (7, -3) .
DECIMAL NUMERIC NUMBER. :
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DEC[ (<>[,<>])]
NUMERIC[ (<>[,<>])]
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1.5.3. . SQL. . Oracle DATE . . : DATE -, .
DATE : , . , '03.05.1999' '12/06/1989', '03-nov-1999', '03-apr-99'.
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1.5.4. (NULL). , SQL NULL. " NULL ". , NULL , . , - . , NULL.
, - , , , - NULL - .
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(NULL), ( " NULL").
IS NULL IS NOT NULL ( "=" ).
, NULL , (NULL).
