Conversion functions

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GoogleSQL for Bigtable supports conversion functions. These data type conversions are explicit, but some conversions can happen implicitly. You can learn more about implicit and explicit conversion here.

Function list

Name	Summary
`ARRAY_TO_STRING`	Produces a concatenation of the elements in an array as a `STRING` value. For more information, see Array functions.
`CAST`	Convert the results of an expression to the given type.
`CHR`	Converts a Unicode code point to a character. For more information, see String functions.
`CODE_POINTS_TO_BYTES`	Converts an array of extended ASCII code points to a `BYTES` value. For more information, see String aggregate functions.
`CODE_POINTS_TO_STRING`	Converts an array of extended ASCII code points to a `STRING` value. For more information, see String aggregate functions.
`DATE_FROM_UNIX_DATE`	Interprets an `INT64` expression as the number of days since 1970-01-01. For more information, see Date functions.
`FROM_BASE32`	Converts a base32-encoded `STRING` value into a `BYTES` value. For more information, see String functions.
`FROM_BASE64`	Converts a base64-encoded `STRING` value into a `BYTES` value. For more information, see String functions.
`FROM_HEX`	Converts a hexadecimal-encoded `STRING` value into a `BYTES` value. For more information, see String functions.
`PARSE_DATE`	Converts a `STRING` value to a `DATE` value. For more information, see Date functions.
`PARSE_TIMESTAMP`	Converts a `STRING` value to a `TIMESTAMP` value. For more information, see Timestamp functions.
`SAFE_CAST`	Similar to the `CAST` function, but returns `NULL` when a runtime error is produced.
`SAFE_CONVERT_BYTES_TO_STRING`	Converts a `BYTES` value to a `STRING` value and replace any invalid UTF-8 characters with the Unicode replacement character, `U+FFFD`. For more information, see String functions.
`STRING` (Timestamp)	Converts a `TIMESTAMP` value to a `STRING` value. For more information, see Timestamp functions.
`TIMESTAMP_MICROS`	Converts the number of microseconds since 1970-01-01 00:00:00 UTC to a `TIMESTAMP`. For more information, see Timestamp functions.
`TIMESTAMP_MILLIS`	Converts the number of milliseconds since 1970-01-01 00:00:00 UTC to a `TIMESTAMP`. For more information, see Timestamp functions.
`TIMESTAMP_SECONDS`	Converts the number of seconds since 1970-01-01 00:00:00 UTC to a `TIMESTAMP`. For more information, see Timestamp functions.
`TO_BASE32`	Converts a `BYTES` value to a base32-encoded `STRING` value. For more information, see String functions.
`TO_BASE64`	Converts a `BYTES` value to a base64-encoded `STRING` value. For more information, see String functions.
`TO_CODE_POINTS`	Converts a `STRING` or `BYTES` value into an array of extended ASCII code points. For more information, see String functions.
`TO_HEX`	Converts a `BYTES` value to a hexadecimal `STRING` value. For more information, see String functions.
`TO_INT64`	Converts the big-endian bytes of a 64-bit signed integer into an `INT64` value. For more information, see String functions.
`TO_JSON_STRING`	Converts a SQL value to a JSON-formatted `STRING` value. For more information, see JSON functions.
`TO_VECTOR32`	Converts the big-endian bytes of one or more 32-bit IEEE 754 floating point numbers into an `ARRAY<FLOAT32>` value. For more information, see String functions.
`TO_VECTOR64`	Converts the big-endian bytes of one or more 64-bit IEEE 754 floating point numbers into an `ARRAY<FLOAT64>` value. For more information, see String functions.
`UNIX_DATE`	Converts a `DATE` value to the number of days since 1970-01-01. For more information, see Date functions.
`UNIX_MICROS`	Converts a `TIMESTAMP` value to the number of microseconds since 1970-01-01 00:00:00 UTC. For more information, see Timestamp functions.
`UNIX_MILLIS`	Converts a `TIMESTAMP` value to the number of milliseconds since 1970-01-01 00:00:00 UTC. For more information, see Timestamp functions.
`UNIX_SECONDS`	Converts a `TIMESTAMP` value to the number of seconds since 1970-01-01 00:00:00 UTC. For more information, see Timestamp functions.

`CAST`

CAST(expression AS typename)

Description

Cast syntax is used in a query to indicate that the result type of an expression should be converted to some other type.

When using CAST, a query can fail if GoogleSQL is unable to perform the cast. If you want to protect your queries from these types of errors, you can use SAFE_CAST.

Casts between supported types that do not successfully map from the original value to the target domain produce runtime errors. For example, casting BYTES to STRING where the byte sequence is not valid UTF-8 results in a runtime error.

Examples

The following query results in "true" if x is 1, "false" for any other non-NULL value, and NULL if x is NULL.

CAST(x=1 AS STRING)

CAST AS ARRAY

CAST(expression AS ARRAY<element_type>)

Description

GoogleSQL supports casting to ARRAY. The expression parameter can represent an expression for these data types:

ARRAY

Conversion rules

From	To	Rule(s) when casting `x`
`ARRAY`	`ARRAY`	Must be the exact same array type.

CAST AS BOOL

CAST(expression AS BOOL)

Description

GoogleSQL supports casting to BOOL. The expression parameter can represent an expression for these data types:

INT64
BOOL
STRING

Conversion rules

From	To	Rule(s) when casting `x`
INT64	`BOOL`	Returns `FALSE` if `x` is `0`, `TRUE` otherwise.
`STRING`	`BOOL`	Returns `TRUE` if `x` is `"true"` and `FALSE` if `x` is `"false"` All other values of `x` are invalid and throw an error instead of casting to a boolean. A string is case-insensitive when converting to a boolean.

CAST AS BYTES

CAST(expression AS BYTES)

Description

GoogleSQL supports casting to BYTES. The expression parameter can represent an expression for these data types:

BYTES
STRING

Conversion rules

From	To	Rule(s) when casting `x`
`STRING`	`BYTES`	Strings are cast to bytes using UTF-8 encoding. For example, the string "©", when cast to bytes, would become a 2-byte sequence with the hex values C2 and A9.

CAST AS DATE

CAST(expression AS DATE)

Description

GoogleSQL supports casting to DATE. The expression parameter can represent an expression for these data types:

STRING
TIMESTAMP

Conversion rules

From	To	Rule(s) when casting `x`
`STRING`	`DATE`	When casting from string to date, the string must conform to the supported date literal format, and is independent of time zone. If the string expression is invalid or represents a date that is outside of the supported min/max range, then an error is produced.
`TIMESTAMP`	`DATE`	Casting from a timestamp to date effectively truncates the timestamp as of the default time zone.

CAST AS FLOAT64

CAST(expression AS FLOAT64)

CAST(expression AS FLOAT32)

Description

GoogleSQL supports casting to floating point types. The expression parameter can represent an expression for these data types:

INT64
FLOAT32
FLOAT64
STRING

Conversion rules

From	To	Rule(s) when casting `x`
INT64	FLOAT64	Returns a close but potentially not exact floating point value.
`STRING`	FLOAT64	Returns `x` as a floating point value, interpreting it as having the same form as a valid floating point literal. Also supports casts from `"[+,-]inf"` to `[,-]Infinity`, `"[+,-]infinity"` to `[,-]Infinity`, and `"[+,-]nan"` to `NaN`. Conversions are case-insensitive.

CAST AS INT64

CAST(expression AS INT64)

Description

GoogleSQL supports casting to integer types. The expression parameter can represent an expression for these data types:

INT64
FLOAT32
FLOAT64
ENUM
BOOL
STRING

Conversion rules

From	To	Rule(s) when casting `x`
FLOAT64	INT64	Returns the closest integer value. Halfway cases such as 1.5 or -0.5 round away from zero.
`BOOL`	INT64	Returns `1` if `x` is `TRUE`, `0` otherwise.
`STRING`	INT64	A hex string can be cast to an integer. For example, `0x123` to `291` or `-0x123` to `-291`.

Examples

If you are working with hex strings (0x123), you can cast those strings as integers:

SELECT '0x123' as hex_value, CAST('0x123' as INT64) as hex_to_int;

/*-----------+------------*
 | hex_value | hex_to_int |
 +-----------+------------+
 | 0x123     | 291        |
 *-----------+------------*/

SELECT '-0x123' as hex_value, CAST('-0x123' as INT64) as hex_to_int;

/*-----------+------------*
 | hex_value | hex_to_int |
 +-----------+------------+
 | -0x123    | -291       |
 *-----------+------------*/

CAST AS STRING

CAST(expression AS STRING)

Description

GoogleSQL supports casting to STRING. The expression parameter can represent an expression for these data types:

INT64
FLOAT32
FLOAT64
ENUM
BOOL
BYTES
DATE
TIMESTAMP
STRING

Conversion rules

From	To	Rule(s) when casting `x`
FLOAT64	`STRING`	Returns an approximate string representation. A returned `NaN` or `0` will not be signed.
`BOOL`	`STRING`	Returns `"true"` if `x` is `TRUE`, `"false"` otherwise.
`BYTES`	`STRING`	Returns `x` interpreted as a UTF-8 string. For example, the bytes literal `b'\xc2\xa9'`, when cast to a string, is interpreted as UTF-8 and becomes the unicode character "©". An error occurs if `x` is not valid UTF-8.
`ENUM`	`STRING`	Returns the canonical enum value name of `x`. If an enum value has multiple names (aliases), the canonical name/alias for that value is used.
`DATE`	`STRING`	Casting from a date type to a string is independent of time zone and is of the form `YYYY-MM-DD`.
`TIMESTAMP`	`STRING`	When casting from timestamp types to string, the timestamp is interpreted using the default time zone, UTC. The number of subsecond digits produced depends on the number of trailing zeroes in the subsecond part: the CAST function will truncate zero, three, or six digits.

Examples

SELECT CAST(CURRENT_DATE() AS STRING) AS current_date

/*---------------*
 | current_date  |
 +---------------+
 | 2021-03-09    |
 *---------------*/

CAST AS TIMESTAMP

CAST(expression AS TIMESTAMP)

Description

GoogleSQL supports casting to TIMESTAMP. The expression parameter can represent an expression for these data types:

STRING
TIMESTAMP

Conversion rules

From	To	Rule(s) when casting `x`
`STRING`	`TIMESTAMP`	When casting from string to a timestamp, `string_expression` must conform to the supported timestamp literal formats, or else a runtime error occurs. The `string_expression` may itself contain a time zone. If there is a time zone in the `string_expression`, that time zone is used for conversion, otherwise the default time zone, UTC, is used. If the string has fewer than six digits, then it is implicitly widened. An error is produced if the `string_expression` is invalid, has more than six subsecond digits (i.e., precision greater than microseconds), or represents a time outside of the supported timestamp range.
`DATE`	`TIMESTAMP`	Casting from a date to a timestamp interprets `date_expression` as of midnight (start of the day) in the default time zone, UTC.

Examples

The following example casts a string-formatted timestamp as a timestamp:

SELECT CAST("2020-06-02 17:00:53.110+00:00" AS TIMESTAMP) AS as_timestamp

-- Results depend upon where this query was executed.
/*-----------------------------*
 | as_timestamp                |
 +-----------------------------+
 | 2020-06-03 00:00:53.110 UTC |
 *-----------------------------*/

`SAFE_CAST`

SAFE_CAST(expression AS typename)

Description

When using CAST, a query can fail if GoogleSQL is unable to perform the cast. For example, the following query generates an error:

SELECT CAST("apple" AS INT64) AS not_a_number;

If you want to protect your queries from these types of errors, you can use SAFE_CAST. SAFE_CAST replaces runtime errors with NULLs. However, during static analysis, impossible casts between two non-castable types still produce an error because the query is invalid.

SELECT SAFE_CAST("apple" AS INT64) AS not_a_number;

/*--------------*
 | not_a_number |
 +--------------+
 | NULL         |
 *--------------*/

If you are casting from bytes to strings, you can also use the function, SAFE_CONVERT_BYTES_TO_STRING. Any invalid UTF-8 characters are replaced with the unicode replacement character, U+FFFD.