Karpova_bazy_dannyh

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. 3.2.

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. 3.3 2

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. 3.3.

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(DDL, Data Definition Language) (DML,

Data Manipulation Language).

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, . DBD (Data Base Definition):

DBD Name = < >. ACCESS = < >

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5 : HSAM hierarchical sequential access method (), HIS AM hierarchical index sequential access method (-), HDAM hierarchical direct access method (), HIDAM hierarchical index direct access method (-), INDEX - .

, :

DATA SET DD1 = < , >, DEVICE =< >,

[OVFLW = < >]

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PARENT 0 ().

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START = < , >.

BYTES = <>.

TYPE = {X | | }.

SEQ ,

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. TYPE . -

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: DBOGEN

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FINISH ; END .

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. , program communication bloc :

DBD NAME = < ()> , ACCESS =LOGICAL DATA SET = LOGICAL.

SEGM NAME = <>. PARENT =<

>, SOURSE =(, )

DBDGEN FINISH END

- , «» (PSB, program specifi-

cation block).

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37

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(. . 3.5).

. 3.5. «»

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GET UNIQUE <> WHERE <>:

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<>.<>0 <constant >;

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{& , V}.

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$600,

10 .

GET UNIQUE WHERE . <= $600 AND . >=10

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GET NEXT <> WHERE <> :

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$500.

GET UNIQUE WHERE . >= $500

WHILE NOT FAIL () D0 PRINT . . GET NEXT

END

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GET NEXT <> WITHIN PARENT [where <. >]

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10 10 .

GET UNIQUE WHERE . = 1

GET NEXT WITHIN PARENT WHERE . = "" GET NEXT WITHIN PARENT

WHERE . = 10 AND

. = AND

. > 10 While Not Fail () D0 Get Next Within Parent

end

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GET HOLD NEXT [WHERE <>]

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INSERT <>

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1975 CODASYL (Conference of Data System Languages), - .

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, - 12.