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69 lines
2.2 KiB
Text
69 lines
2.2 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 `date`, `date_period`, `time_duration`, `ip` or `version` 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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[discrete]
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[[esql-implicit-casting-example]]
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==== Implicit casting example
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Implicit casting automatically converts string literals to the target data type. This allows users to specify string values for types like `date`, `date_period`, `time_duration`, `ip` and `version` in their 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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[discrete]
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[[esql-implicit-casting-supported-operations]]
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==== Operations that support implicit casting
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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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|ScalarFunctions|Operators|<<esql-group-functions, GroupingFunctions>>|<<esql-agg-functions, AggregateFunctions>>
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DATE|Y|Y|Y|N
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DATE_PERIOD/TIME_DURATION|Y|N|Y|N
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IP|Y|Y|Y|N
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VERSION|Y|Y|Y|N
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BOOLEAN|Y|Y|Y|N
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|===
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ScalarFunctions includes:
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* <<esql-conditional-functions-and-expressions, Conditional Functions and Expressions>>
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* <<esql-date-time-functions, Date and Time Functions>>
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* <<esql-ip-functions, IP Functions>>
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Operators includes:
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* <<esql-binary-operators, Binary Operators>>
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* <<esql-unary-operators, Unary Operator>>
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* <<esql-in-operator, IN>>
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