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This copies the first line of the description of each command to just under the syntax so that it's "in order", before the `Parameters` section. That way if you are reading from top to bottom you see: ``` syntax short description parameter names and descriptions long description examples ``` I've also removed the `Description` section entirely if the description was just one sentence. So in some cases that just isn't `long description`.
76 lines
1.9 KiB
Text
76 lines
1.9 KiB
Text
[discrete]
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[[esql-eval]]
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=== `EVAL`
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The `EVAL` processing command enables you to append new columns with calculated
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values.
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**Syntax**
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[source,esql]
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----
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EVAL [column1 =] value1[, ..., [columnN =] valueN]
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----
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*Parameters*
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`columnX`::
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The column name.
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`valueX`::
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The value for the column. Can be a literal, an expression, or a
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<<esql-functions,function>>.
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*Description*
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The `EVAL` processing command enables you to append new columns with calculated
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values. `EVAL` supports various functions for calculating values. Refer to
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<<esql-functions,Functions>> for more information.
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*Examples*
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[source.merge.styled,esql]
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----
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include::{esql-specs}/eval.csv-spec[tag=eval]
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----
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[%header.monospaced.styled,format=dsv,separator=|]
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include::{esql-specs}/eval.csv-spec[tag=eval-result]
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|===
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If the specified column already exists, the existing column will be dropped, and
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the new column will be appended to the table:
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[source.merge.styled,esql]
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----
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include::{esql-specs}/eval.csv-spec[tag=evalReplace]
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----
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[%header.monospaced.styled,format=dsv,separator=|]
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|===
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include::{esql-specs}/eval.csv-spec[tag=evalReplace-result]
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|===
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Specifying the output column name is optional. If not specified, the new column
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name is equal to the expression. The following query adds a column named
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`height*3.281`:
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[source.merge.styled,esql]
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----
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include::{esql-specs}/eval.csv-spec[tag=evalUnnamedColumn]
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----
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[%header.monospaced.styled,format=dsv,separator=|]
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include::{esql-specs}/eval.csv-spec[tag=evalUnnamedColumn-result]
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|===
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Because this name contains special characters, <<esql-identifiers,it needs to be
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quoted>> with backticks (+{backtick}+) when using it in subsequent commands:
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[source.merge.styled,esql]
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----
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include::{esql-specs}/eval.csv-spec[tag=evalUnnamedColumnStats]
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----
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[%header.monospaced.styled,format=dsv,separator=|]
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|===
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include::{esql-specs}/eval.csv-spec[tag=evalUnnamedColumnStats-result]
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|===
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