find()
Here’s how to use find() function.
A .find()
Description:
Find a record according to its primary key value.
Syntax:
A.find(k)
Note:
The function finds records from a record sequence/table sequence whose primary key values are k. Use the index table if there is one.
Parameters:
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A |
A record sequence/table sequence |
|
k |
Primary key, which will be written as a sequence if it is a multi-field primary key. |
Options:
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@b |
Enable the binary search. Here, A must be ordered by the primary key; otherwise, the result will be wrong. The index table will be ignored. |
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@k |
Return members of A matching the sequence of key values specified by parameter k |
Return value:
Records
Example:
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A |
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1 |
=demo.query("select * from EMPLOYEE") |
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2 |
=A1.keys(NAME,DEPT) |
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3 |
=A1.find(["Alexis","Sales"]) |
A sequence is used since the key contains two fields |
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4 |
=demo.query("select * from EMPLOYEE") |
This table sequence is ordered by the EID field |
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5 |
=A4.keys(EID) |
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6 |
=A4.find@b(3) |
@b is used to enable the binary search in order to speed up the computation |
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7 |
=A4.find@k(2,15,69,220) |
With @k option, the function returns members matching the specified key values |
Related functions:
T.find( k,… )
Description:
Find the record(s) according to the specified primary key value(s) from a memory table.
Syntax:
T.find(k,…)
Note:
The function finds records where the primary key value is k from memory table T.Use binary search if there isn’t an index.
Parameters:
|
T |
A memory table |
|
k |
The primary key; write multiple keys as a sequence |
Options:
|
@k |
Find multiple records according to multiple primay keys and return them as a record sequence; write multiple primary keys in the format of [[k1,k2],[...],...] |
Return value:
A record/record sequence
Example:
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A |
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1 |
=demo.cursor("select EID,NAME,GENDER from employee where EID< 10") |
Return a cursor |
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2 |
=A1.memory() |
Return a memory table
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3 |
=A2.keys(EID,NAME) |
Set EID and NAME as the keys of the memory table |
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4 |
=A2.find([8,"Megan"]) |
The two primary keys are written as a sequence
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5 |
=A2.keys(EID,GENDER) |
Set EID and GENDER as the keys of the memory table |
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6 |
=A2.find@k([[8,"F"],[2,"F"]]) |
Use @k option to find multiple records
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7 |
=A2.keys(EID) |
Set EID as the key of the memory table |
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8 |
=A2.find(3) |
Find the record where EID is 3
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T.find( k;x:C,.. )
Description:
Find the record(s) according to the specified primary key value(s) from a base table.
Syntax:
T.find(k;x:C,..)
Note:
The function finds the record(s) where key value(s) is k and returns a record/record sequence containing one field C. The key value k can be represented by the first dimension value which can uniquely identify a record.
Parameters:
|
T |
Base table |
|
k |
The primary key; write multiple keys as a sequence |
|
x |
Column name; retrieve all field if omitted |
|
C |
Column alias; can be omitted |
Options:
|
@k |
Find multiple records according to multiple primay keys and return them as a record sequence; write multiple primary keys in the format of [[k1,k2],[...],...] |
Return value:
A record/record sequence
Example:
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A |
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1 |
=file("E:/find1.ctx") |
Return a cursor |
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2 |
=A1.create() |
Open a composite table’s base table whose dimensions are EID and NAME |
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3 |
=A2.find([8,"Megan"]) |
Since parameter x is absent, the function returns all columns
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4 |
=A2.find([8,"Megan"];EID,SALARY) |
Return specified columns
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5 |
=A2.find@k([[4,"Emily"], [8,"Megan"]];EID,SALARY) |
Find multiple records with @k option
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