sortx()
Here’s how to use sortx() function.
ch.sortx()
Description:
Sort records in a channel.
Syntax:
ch.sortx(x,…)
Note:
The function sorts records in channel ch by expression x,… and returns the sorted records as a channel. This is a function for directly getting a result set from the channel.
Parameter:
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ch |
Channel |
|
x |
An expression, according to which the records in a given channel is sorted in ascending order |
Return value:
Channel
Example:
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A |
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1 |
=demo.cursor("select EID,NAME,DEPT,SALARY from EMPLOYEE order by EID desc") |
Return a cursor with desired records |
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2 |
=channel() |
Create a channel |
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3 |
=A2.sortx(SALARY,EID) |
Sort records in the channel by SALARY field and EID field |
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4 |
=A1.push(A2) |
Push data in A1’s cursor into the channel |
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5 |
=A1.fetch() |
Fetch data from A1’s cursor |
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6 |
=A2.result() |
Return result as a cursor |
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7 |
=A6.fetch() |
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cs.sortx()
Description:
Sort data of a cursor.
Syntax:
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cs.sortx(x,…;n) |
Note:
The function sorts cursor cs by expression x, and returns result as a cursor. The cursor the function returns is irreversible.
Parameter:
|
cs |
A cursor |
|
x |
An expression to sort members of cursor cs in ascending order |
|
n |
Number of buffer rows; if the number of groups reaches n, write the grouping result to a temporary file; its value will be n times of the default if it is less than 1; by default, esProc will auto-compute the value |
Option:
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@0 |
Put records with null values at the end; @0 and @n can’t work together |
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@n |
It can only be used to make the calculation faster when the value of expression x is a positive integer over which group of records can be directly numbered. @0 and @n can’t work together |
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@g |
Treat parameter n as the segmentation expression by which records are first segmented and then grouped and sorted |
Return value:
A cursor
Example:
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A |
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1 |
=demo.cursor("select NAME,BIRTHDAY,HIREDATE from Employee") |
Return retrieved data as a cursor |
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2 |
=A1.sortx(BIRTHDAY) |
Sort the cursor’s BIRTHDAY field |
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3 |
=A2.fetch() |
Retrieve data from cursor A2 |
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4 |
=demo.cursor("select * from DEPT") |
Return retrieved data as a cursor |
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5 |
=A4.sortx@0(FATHER).fetch() |
Sort records in the cursor by FATHER field and put the one with null value at the end |
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6 |
=A4.sortx@g(DEPTID;FATHER==12).fetch() |
Group records according to whether FATHER value is 12 and then sort each group by DEPTID |
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7 |
=A1.sortx(BIRTHDAY;2) |
Sort BIRTHDAY field in the cursor; since data is divided into two groups to be processed, write the grouping result to a temporary file |
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8 |
=demo.cursor("select * from SCORES") |
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|
9 |
=A8.sortx@n(SCORE).fetch() |
The result of fetching SCORE values are integers; here @n option is used to speed up the sorting |
Related function:
cs.sortx()
Description:
Sort a cluster cursor.
Syntax:
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cs.sortx(x,…;n) |
|
Note:
The function sorts cluster cursor cs by expression x and returns a clustrer cursor.
Option:
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@c |
Won’t merge result sets returned by the nodes but return a cluster cursor segmented in the same way |
Parameter:
|
cs |
A cluster cursor |
|
x |
An expression by which records in a specified cluster cursor are sorted in ascending order |
|
n
|
Number of buffer rows; if the number of groups reaches n, write the grouping result to a temporary file; its value will be n times of the default if it is less than 1; by default esProc will uto-compute the value |
Return value:
A cluster cursor
Example:
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A |
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1 |
[192.168.0.110:8281,192.168.18.143:8281] |
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2 |
=file("emp.ctx", A1) |
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3 |
=A2.open() |
Open a cluster composite table file |
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4 |
=A3.cursor() |
Return a cluster cursor |
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5 |
=A4.sortx(EID) |
Sort A4’s cluster cursor by EID and return result also as a cluster cursor |