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53 lines
1.8 KiB
Text
53 lines
1.8 KiB
Text
[[esql-implicit-casting]]
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=== {esql} implicit casting
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++++
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<titleabbrev>Implicit casting</titleabbrev>
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++++
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Often users will input `datetime`, `ip`, `version`, or geospatial objects as simple strings in their queries for use in predicates, functions, or expressions. {esql} provides <<esql-type-conversion-functions, type conversion functions>> to explicitly convert these strings into the desired data types.
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Without implicit casting users must explicitly code these `to_X` functions in their queries, when string literals don't match the target data types they are assigned or compared to. Here is an example of using `to_datetime` to explicitly perform a data type conversion.
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[source.merge.styled,esql]
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----
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FROM employees
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| EVAL dd_ns1=date_diff("day", to_datetime("2023-12-02T11:00:00.00Z"), birth_date)
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| SORT emp_no
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| KEEP dd_ns1
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| LIMIT 1
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----
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Implicit casting improves usability, by automatically converting string literals to the target data type. This is most useful when the target data type is `datetime`, `ip`, `version` or a geo spatial. It is natural to specify these as a string in queries.
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The first query can be coded without calling the `to_datetime` function, as follows:
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[source.merge.styled,esql]
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----
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FROM employees
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| EVAL dd_ns1=date_diff("day", "2023-12-02T11:00:00.00Z", birth_date)
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| SORT emp_no
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| KEEP dd_ns1
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| LIMIT 1
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----
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[float]
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=== Implicit casting support
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The following table details which {esql} operations support implicit casting for different data types.
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[%header.monospaced.styled,format=dsv,separator=|]
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|===
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||ScalarFunction|BinaryComparison|ArithmeticOperation|InListPredicate|AggregateFunction
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|DATETIME|Y|Y|Y|Y|N
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|DOUBLE|Y|N|N|N|N
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|LONG|Y|N|N|N|N
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|INTEGER|Y|N|N|N|N
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|IP|Y|Y|Y|Y|N
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|VERSION|Y|Y|Y|Y|N
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|GEO_POINT|Y|N|N|N|N
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|GEO_SHAPE|Y|N|N|N|N
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|CARTESIAN_POINT|Y|N|N|N|N
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|CARTESIAN_SHAPE|Y|N|N|N|N
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|BOOLEAN|Y|Y|Y|Y|N
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|===
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