ch.()
Description:
Compute a given expression over each member in a channel.
Syntax:
ch.(x)
ch.() Return the channel ch itself
Note:
The function computes a given expression over each member in a channel and returns the results as a channel. Use ~ to reference the current member in the expression. This is an attached computation.
Parameter:
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ch |
Channel |
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x |
An expression, which is a field name generally or a legal expression consisting of field names; use ~ to reference the current record. |
Return value:
A new channel consisting of the results of computing the expression over each member of a channel
Example:
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A |
B |
C |
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1 |
=demo.cursor("select EID,NAME,BIRTHDAY,SALARY from EMPLOYEE where EID<10") |
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2 |
=channel() |
=channel() |
=channel() |
Create a channel |
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3 |
=A2.(age(BIRTHDAY)) |
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Compute age(BIRTHDAY) on BIRTHDAY’s members in A2’s channel and return result to the channel |
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4 |
=A2.fetch() |
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Attach ch.fetch() function that gets the final result set to A2’s channel to fetch and store the existing data in the channel |
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5 |
=B2.(SALARY) |
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Compute SALARY column in B2’s channel |
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6 |
=B2.(~*~) |
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Use ~ to reference the current member of a sequence to compute SALARY*SALARY and return result to B2’s channel |
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7 |
=B2.fetch() |
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Attach ch.fetch() function that gets the final result set to B2’s channel to fetch and store the existing data in the channel |
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8 |
=C2.() |
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Return channel C2 |
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9 |
=C2.fetch() |
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Attach ch.fetch() function that gets the final result set to C2’s channel to fetch and store the existing data in the channel |
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10 |
=A1.push(A2,B2,C2) |
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Be ready to push data in A1’s cursor into channel A2, B2 and C2, but the action needs to wait. |
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11 |
=A1.fetch() |
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Data in A1’s cursor is pushed into the channel and operations are performed as data retrieval is performed over A1 |
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12 |
=A2.result() |
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13 |
=B2.result() |
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14 |
=C2.result() |
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