[[esql-implicit-casting]] === {esql} implicit casting ++++ Implicit casting ++++ Often users will input `date`, `ip`, `version`, `date_period` or `time_duration` as simple strings in their queries for use in predicates, functions, or expressions. {esql} provides <> to explicitly convert these strings into the desired data types. 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. [source.merge.styled,esql] ---- FROM employees | EVAL dd_ns1=date_diff("day", to_datetime("2023-12-02T11:00:00.00Z"), birth_date) | SORT emp_no | KEEP dd_ns1 | LIMIT 1 ---- Implicit casting improves usability, by automatically converting string literals to the target data type. This is most useful when the target data type is `date`, `ip`, `version`, `date_period` or `time_duration`. It is natural to specify these as a string in queries. The first query can be coded without calling the `to_datetime` function, as follows: [source.merge.styled,esql] ---- FROM employees | EVAL dd_ns1=date_diff("day", "2023-12-02T11:00:00.00Z", birth_date) | SORT emp_no | KEEP dd_ns1 | LIMIT 1 ---- [float] === Implicit casting support The following table details which {esql} operations support implicit casting for different data types. [%header.monospaced.styled,format=dsv,separator=|] |=== ||ScalarFunction*|Operator*|<>|<> |DATE|Y|Y|Y|N |IP|Y|Y|Y|N |VERSION|Y|Y|Y|N |BOOLEAN|Y|Y|Y|N |DATE_PERIOD/TIME_DURATION|Y|N|Y|N |=== ScalarFunction* includes: <> <> <> Operator* includes: <> <> <>