T .update( P )
Description:
Update records in an entity table.
Syntax:
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T.update(P) |
Note:
The function updates entity table T’s records by matching keys in T and record sequence P; P and T should have same structure. If a key value in P doesn’t exist in T, append or insert the corresponding record in T.
Parameters:
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T |
A composite table’s entity table |
|
P |
A table sequence/record sequence having same structure as T |
Options:
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@i |
Only append or insert non-matching records and ignore the matching ones |
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@u |
Only update the matching records and ignore the non-matching ones |
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@n |
Return records that are updated and inserted |
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@w |
When parameter P is a cursor having same order as the original entity table, update the latter’s fields that P has; only valid for column-wise storage format and no records should be added |
An entity table
Example:
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|
A |
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|
1 |
=file("emp.ctx") |
Generate a composite table file |
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2 |
=A1.create@y(#EID,NAME) |
Create the composite table’s base table |
|
3 |
=connect("demo").cursor("select EID,NAME from employee where EID<20") |
Return a cursor |
|
4 |
=A2.append@i(A3) |
Append data in A3’s cursor to A2’s base table |
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5 |
=A2.attach(table3,SURNAME) |
Add attached table table3 that has two fields – EID, which is the key, and SURNAME, to the base table |
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6 |
=connect("demo").cursor("select EID,SURNAME from employee where EID< 5") |
Return a cursor |
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7 |
=A5.append@i(A6) |
Append data in A6’s cursor to A5’s pseudo table |
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8 |
=A2.cursor().fetch() |
View data in the base table:
|
|
9 |
=A5.cursor().fetch() |
View data in the attached table:
|
|
10 |
=create(EID,NAME).record([1,"A",21,"B"]) |
Return a table sequence |
|
11 |
=A2.update(A10) |
Update the base table using A8’s table sequence |
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12 |
=A2.cursor().fetch() |
View data in the base table again:
|
|
13 |
=create(EID,SURNAME).record([2,"aa",10,"bb"]) |
Return a table sequence |
|
14 |
=A5.update@in(A13) |
With @i option, only handles insert and ignore records with same key values; the cooperation with @n option makes the function return only the inserted records
|
|
15 |
=A5.cursor().fetch() |
View data in the attached table again:
|
|
16 |
=create(EID,SURNAME).record([1,"ss",6,"cc"]) |
Return a table sequence |
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17 |
=A5.update@un(A16) |
With @u option, only handles update and ignore records with different key values; the cooperation with @n option makes the function return only the updated records
|
|
18 |
=A5.cursor().fetch() |
View data in the attached table:
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