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---------
Co-authored-by: Liam Thompson <32779855+leemthompo@users.noreply.github.com>
Co-authored-by: Liam Thompson <leemthompo@gmail.com>
Co-authored-by: Martijn Laarman <Mpdreamz@gmail.com>
Co-authored-by: István Zoltán Szabó <szabosteve@gmail.com>
61 lines
2.8 KiB
Markdown
61 lines
2.8 KiB
Markdown
---
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navigation_title: "Implicit casting"
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mapped_pages:
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- https://www.elastic.co/guide/en/elasticsearch/reference/current/esql-implicit-casting.html
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---
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# {{esql}} implicit casting [esql-implicit-casting]
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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 [type conversion functions](/reference/query-languages/esql/esql-functions-operators.md#esql-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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```esql
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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 example [esql-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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```esql
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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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## Operations that support implicit casting [esql-implicit-casting-supported-operations]
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The following table details which {{esql}} operations support implicit casting for different data types.
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| | ScalarFunctions | Operators | [GroupingFunctions](/reference/query-languages/esql/esql-functions-operators.md#esql-group-functions) | [AggregateFunctions](/reference/query-languages/esql/esql-functions-operators.md#esql-agg-functions) |
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| --- | --- | --- | --- | --- |
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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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ScalarFunctions includes:
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* [Conditional Functions and Expressions](/reference/query-languages/esql/esql-functions-operators.md#esql-conditional-functions-and-expressions)
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* [Date and Time Functions](/reference/query-languages/esql/esql-functions-operators.md#esql-date-time-functions)
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* [IP Functions](/reference/query-languages/esql/esql-functions-operators.md#esql-ip-functions)
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Operators includes:
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* [Binary Operators](/reference/query-languages/esql/esql-functions-operators.md#esql-binary-operators)
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* [Unary Operator](/reference/query-languages/esql/esql-functions-operators.md#esql-unary-operators)
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* [IN](/reference/query-languages/esql/esql-functions-operators.md#esql-in-operator)
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