---
layout: docu
redirect_from:
- /docs/test/functions/utility
- /docs/test/functions/utility/
- /docs/sql/functions/utility
title: Utility Functions
---
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## Scalar Utility Functions
The functions below are difficult to categorize into specific function types and are broadly useful.
| Name | Description |
|:--|:-------|
| [`alias(column)`](#aliascolumn) | Return the name of the column. |
| [`checkpoint(database)`](#checkpointdatabase) | Synchronize WAL with file for (optional) database without interrupting transactions. |
| [`coalesce(expr, ...)`](#coalesceexpr-) | Return the first expression that evaluates to a non-`NULL` value. Accepts 1 or more parameters. Each expression can be a column, literal value, function result, or many others. |
| [`constant_or_null(arg1, arg2)`](#constant_or_nullarg1-arg2) | If `arg2` is `NULL`, return `NULL`. Otherwise, return `arg1`. |
| [`count_if(x)`](#count_ifx) | Aggregate function; rows contribute 1 if `x` is `true` or a non-zero number, else 0. |
| [`current_catalog()`](#current_catalog) | Return the name of the currently active catalog. Default is memory. |
| [`current_schema()`](#current_schema) | Return the name of the currently active schema. Default is main. |
| [`current_schemas(boolean)`](#current_schemasboolean) | Return list of schemas. Pass a parameter of `true` to include implicit schemas. |
| [`current_setting('setting_name')`](#current_settingsetting_name) | Return the current value of the configuration setting. |
| [`currval('sequence_name')`](#currvalsequence_name) | Return the current value of the sequence. Note that `nextval` must be called at least once prior to calling `currval`. |
| [`error(message)`](#errormessage) | Throws the given error `message`. |
| [`equi_width_bins(min, max, bincount, nice := false)`](#equi_width_binsmin-max-bincount-nice--false) | Returns the upper boundaries of a partition of the interval `[min, max]` into `bin_count` equal-sized subintervals (for use with, e.g., [`histogram`]({% link docs/stable/sql/functions/aggregates.md %}#histogramargboundaries)). If `nice = true`, then `min`, `max`, and `bincount` may be adjusted to produce more aesthetically pleasing results. |
| [`force_checkpoint(database)`](#force_checkpointdatabase) | Synchronize WAL with file for (optional) database interrupting transactions. |
| [`gen_random_uuid()`](#gen_random_uuid) | Alias of `uuid`. Return a random UUID similar to this: `eeccb8c5-9943-b2bb-bb5e-222f4e14b687`. |
| [`getenv(var)`](#getenvvar) | Returns the value of the environment variable `var`. Only available in the [command line client]({% link docs/stable/clients/cli/overview.md %}). |
| [`hash(value)`](#hashvalue) | Returns a `UBIGINT` with the hash of the `value`. |
| [`icu_sort_key(string, collator)`](#icu_sort_keystring-collator) | Surrogate [sort key](https://unicode-org.github.io/icu/userguide/collation/architecture.html#sort-keys) used to sort special characters according to the specific locale. Collator parameter is optional. Only available when the ICU extension is installed. |
| [`if(a, b, c)`](#ifa-b-c) | Ternary conditional operator. |
| [`ifnull(expr, other)`](#ifnullexpr-other) | A two-argument version of coalesce. |
| [`is_histogram_other_bin(arg)`](#is_histogram_other_binarg) | Returns `true` when `arg` is the "catch-all element" of its datatype for the purpose of the [`histogram_exact`]({% link docs/stable/sql/functions/aggregates.md %}#histogram_exactargelements) function, which is equal to the "right-most boundary" of its datatype for the purpose of the [`histogram`]({% link docs/stable/sql/functions/aggregates.md %}#histogramargboundaries) function. |
| [`md5(string)`](#md5string) | Returns the MD5 hash of the `string` as a `VARCHAR`. |
| [`md5_number(string)`](#md5_numberstring) | Returns the MD5 hash of the `string` as a `HUGEINT`. |
| [`md5_number_lower(string)`](#md5_number_lowerstring) | Returns the lower 64-bit segment of the MD5 hash of the `string` as a `BIGINT`. |
| [`md5_number_higher(string)`](#md5_number_higherstring) | Returns the higher 64-bit segment of the MD5 hash of the `string` as a `BIGINT`. |
| [`nextval('sequence_name')`](#nextvalsequence_name) | Return the following value of the sequence. |
| [`nullif(a, b)`](#nullifa-b) | Return `NULL` if `a = b`, else return `a`. Equivalent to `CASE WHEN a = b THEN NULL ELSE a END`. |
| [`pg_typeof(expression)`](#pg_typeofexpression) | Returns the lower case name of the data type of the result of the expression. For PostgreSQL compatibility. |
| [`query(`*`query_string_literal`*`)`](#queryquery_string_literal) | Table function that parses and executes the query defined in *`query_string_literal`*. Only literal strings are allowed. Warning: this function allows invoking arbitrary queries, potentially altering the database state. |
| [`query_table(`*`tbl_name`*`)`](#query_tabletbl_name) | Table function that returns the table given in *`tbl_name`*. |
| [`query_table(`*`tbl_names`*`, [`*`by_name`*`])`](#query_tabletbl_names-by_name) | Table function that returns the union of tables given in *`tbl_names`*. If the optional *`by_name`* parameter is set to `true`, it uses [`UNION ALL BY NAME`]({% link docs/stable/sql/query_syntax/setops.md %}#union-all-by-name) semantics. |
| [`read_blob(source)`](#read_blobsource) | Returns the content from `source` (a filename, a list of filenames, or a glob pattern) as a `BLOB`. See the [`read_blob` guide]({% link docs/stable/guides/file_formats/read_file.md %}#read_blob) for more details. |
| [`read_text(source)`](#read_textsource) | Returns the content from `source` (a filename, a list of filenames, or a glob pattern) as a `VARCHAR`. The file content is first validated to be valid UTF-8. If `read_text` attempts to read a file with invalid UTF-8 an error is thrown suggesting to use `read_blob` instead. See the [`read_text` guide]({% link docs/stable/guides/file_formats/read_file.md %}#read_text) for more details. |
| [`sha1(string)`](#sha1string) | Returns a `VARCHAR` with the SHA-1 hash of the `string`. |
| [`sha256(string)`](#sha256string) | Returns a `VARCHAR` with the SHA-256 hash of the `string`. |
| [`stats(expression)`](#statsexpression) | Returns a string with statistics about the expression. Expression can be a column, constant, or SQL expression. |
| [`txid_current()`](#txid_current) | Returns the current transaction's identifier, a `BIGINT` value. It will assign a new one if the current transaction does not have one already. |
| [`typeof(expression)`](#typeofexpression) | Returns the name of the data type of the result of the expression. |
| [`uuid()`](#uuid) | Return a random UUID similar to this: `eeccb8c5-9943-b2bb-bb5e-222f4e14b687`. |
| [`version()`](#version) | Return the currently active version of DuckDB in this format. |
#### `alias(column)`
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| **Description** | Return the name of the column. |
| **Example** | `alias(column1)` |
| **Result** | `column1` |
#### `checkpoint(database)`
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| **Description** | Synchronize WAL with file for (optional) database without interrupting transactions. |
| **Example** | `checkpoint(my_db)` |
| **Result** | success Boolean |
#### `coalesce(expr, ...)`
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| **Description** | Return the first expression that evaluates to a non-`NULL` value. Accepts 1 or more parameters. Each expression can be a column, literal value, function result, or many others. |
| **Example** | `coalesce(NULL, NULL, 'default_string')` |
| **Result** | `default_string` |
#### `constant_or_null(arg1, arg2)`
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| **Description** | If `arg2` is `NULL`, return `NULL`. Otherwise, return `arg1`. |
| **Example** | `constant_or_null(42, NULL)` |
| **Result** | `NULL` |
#### `count_if(x)`
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| **Description** | Aggregate function; rows contribute 1 if `x` is `true` or a non-zero number, else 0. |
| **Example** | `count_if(42)` |
| **Result** | 1 |
#### `current_catalog()`
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| **Description** | Return the name of the currently active catalog. Default is memory. |
| **Example** | `current_catalog()` |
| **Result** | `memory` |
#### `current_schema()`
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| **Description** | Return the name of the currently active schema. Default is main. |
| **Example** | `current_schema()` |
| **Result** | `main` |
#### `current_schemas(boolean)`
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| **Description** | Return list of schemas. Pass a parameter of `true` to include implicit schemas. |
| **Example** | `current_schemas(true)` |
| **Result** | `['temp', 'main', 'pg_catalog']` |
#### `current_setting('setting_name')`
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| **Description** | Return the current value of the configuration setting. |
| **Example** | `current_setting('access_mode')` |
| **Result** | `automatic` |
#### `currval('sequence_name')`
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| **Description** | Return the current value of the sequence. Note that `nextval` must be called at least once prior to calling `currval`. |
| **Example** | `currval('my_sequence_name')` |
| **Result** | `1` |
#### `error(message)`
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| **Description** | Throws the given error `message`. |
| **Example** | `error('access_mode')` |
#### `equi_width_bins(min, max, bincount, nice := false)`
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| **Description** | Returns the upper boundaries of a partition of the interval `[min, max]` into `bin_count` equal-sized subintervals (for use with, e.g., [`histogram`]({% link docs/stable/sql/functions/aggregates.md %}#histogramargboundaries)). If `nice = true`, then `min`, `max`, and `bincount` may be adjusted to produce more aesthetically pleasing results. |
| **Example** | `equi_width_bins(0.1, 2.7, 4, true)` |
| **Result** | `[0.5, 1.0, 1.5, 2.0, 2.5, 3.0]` |
#### `force_checkpoint(database)`
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| **Description** | Synchronize WAL with file for (optional) database interrupting transactions. |
| **Example** | `force_checkpoint(my_db)` |
| **Result** | success Boolean |
#### `gen_random_uuid()`
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| **Description** | Alias of `uuid`. Return a random UUID similar to this: `eeccb8c5-9943-b2bb-bb5e-222f4e14b687`. |
| **Example** | `gen_random_uuid()` |
| **Result** | various |
#### `getenv(var)`
| **Description** | Returns the value of the environment variable `var`. Only available in the [command line client]({% link docs/stable/clients/cli/overview.md %}). |
| **Example** | `getenv('HOME')` |
| **Result** | `/path/to/user/home` |
#### `hash(value)`
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| **Description** | Returns a `UBIGINT` with the hash of the `value`. |
| **Example** | `hash('π¦')` |
| **Result** | `2595805878642663834` |
#### `icu_sort_key(string, collator)`
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| **Description** | Surrogate [sort key](https://unicode-org.github.io/icu/userguide/collation/architecture.html#sort-keys) used to sort special characters according to the specific locale. Collator parameter is optional. Only available when the ICU extension is installed. |
| **Example** | `icu_sort_key('ΓΆ', 'DE')` |
| **Result** | `460145960106` |
#### `if(a, b, c)`
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| **Description** | Ternary conditional operator; returns b if a, else returns c. Equivalent to `CASE WHEN a THEN b ELSE c END`. |
| **Example** | `if(2 > 1, 3, 4)` |
| **Result** | `3` |
#### `ifnull(expr, other)`
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| **Description** | A two-argument version of coalesce. |
| **Example** | `ifnull(NULL, 'default_string')` |
| **Result** | `default_string` |
#### `is_histogram_other_bin(arg)`
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| **Description** | Returns `true` when `arg` is the "catch-all element" of its datatype for the purpose of the [`histogram_exact`]({% link docs/stable/sql/functions/aggregates.md %}#histogram_exactargelements) function, which is equal to the "right-most boundary" of its datatype for the purpose of the [`histogram`]({% link docs/stable/sql/functions/aggregates.md %}#histogramargboundaries) function. |
| **Example** | `is_histogram_other_bin('')` |
| **Result** | `true` |
#### `md5(string)`
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| **Description** | Returns the MD5 hash of the `string` as a `VARCHAR`. |
| **Example** | `md5('123')` |
| **Result** | `202cb962ac59075b964b07152d234b70` |
#### `md5_number(string)`
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| **Description** | Returns the MD5 hash of the `string` as a `HUGEINT`. |
| **Example** | `md5_number('123')` |
| **Result** | `149263671248412135425768892945843956768` |
#### `md5_number_lower(string)`
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| **Description** | Returns the lower 8 bytes of the MD5 hash of `string` as a `BIGINT`. |
| **Example** | `md5_number_lower('123')` |
| **Result** | `8091599832034528150` |
#### `md5_number_higher(string)`
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| **Description** | Returns the higher 8 bytes of the MD5 hash of `string` as a `BIGINT`. |
| **Example** | `md5_number_higher('123')` |
| **Result** | `6559309979213966368` |
#### `nextval('sequence_name')`
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| **Description** | Return the following value of the sequence. |
| **Example** | `nextval('my_sequence_name')` |
| **Result** | `2` |
#### `nullif(a, b)`
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| **Description** | Return `NULL` if a = b, else return a. Equivalent to `CASE WHEN a = b THEN NULL ELSE a END`. |
| **Example** | `nullif(1+1, 2)` |
| **Result** | `NULL` |
#### `pg_typeof(expression)`
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| **Description** | Returns the lower case name of the data type of the result of the expression. For PostgreSQL compatibility. |
| **Example** | `pg_typeof('abc')` |
| **Result** | `varchar` |
#### `query(query_string_literal)`
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| **Description** | Table function that parses and executes the query defined in `query_string_literal`. Only literal strings are allowed. Warning: this function allows invoking arbitrary queries, potentially altering the database state. |
| **Example** | `query('SELECT 42 AS x')` |
| **Result** | `42` |
#### `query_table(tbl_name)`
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| **Description** | Table function that returns the table given in `tbl_name`. |
| **Example** | `query_table('t1')` |
| **Result** | (the rows of `t1`) |
#### `query_table(tbl_names, [by_name])`
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| **Description** | Table function that returns the union of tables given in `tbl_names`. If the optional `by_name` parameter is set to `true`, it uses [`UNION ALL BY NAME`]({% link docs/stable/sql/query_syntax/setops.md %}#union-all-by-name) semantics. |
| **Example** | `query_table(['t1', 't2'])` |
| **Result** | (the union of the two tables) |
#### `read_blob(source)`
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| **Description** | Returns the content from `source` (a filename, a list of filenames, or a glob pattern) as a `BLOB`. See the [`read_blob` guide]({% link docs/stable/guides/file_formats/read_file.md %}#read_blob) for more details. |
| **Example** | `read_blob('hello.bin')` |
| **Result** | `hello\x0A` |
#### `read_text(source)`
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| **Description** | Returns the content from `source` (a filename, a list of filenames, or a glob pattern) as a `VARCHAR`. The file content is first validated to be valid UTF-8. If `read_text` attempts to read a file with invalid UTF-8 an error is thrown suggesting to use `read_blob` instead. See the [`read_text` guide]({% link docs/stable/guides/file_formats/read_file.md %}#read_text) for more details. |
| **Example** | `read_text('hello.txt')` |
| **Result** | `hello\n` |
#### `sha1(string)`
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| **Description** | Returns a `VARCHAR` with the SHA-1 hash of the `string`. |
| **Example** | `sha1('π¦')` |
| **Result** | `949bf843dc338be348fb9525d1eb535d31241d76` |
#### `sha256(string)`
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| **Description** | Returns a `VARCHAR` with the SHA-256 hash of the `string`. |
| **Example** | `sha256('π¦')` |
| **Result** | `d7a5c5e0d1d94c32218539e7e47d4ba9c3c7b77d61332fb60d633dde89e473fb` |
#### `stats(expression)`
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| **Description** | Returns a string with statistics about the expression. Expression can be a column, constant, or SQL expression. |
| **Example** | `stats(5)` |
| **Result** | `'[Min: 5, Max: 5][Has Null: false]'` |
#### `txid_current()`
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| **Description** | Returns the current transaction's identifier, a `BIGINT` value. It will assign a new one if the current transaction does not have one already. |
| **Example** | `txid_current()` |
| **Result** | various |
#### `typeof(expression)`
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| **Description** | Returns the name of the data type of the result of the expression. |
| **Example** | `typeof('abc')` |
| **Result** | `VARCHAR` |
#### `uuid()`
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| **Description** | Return a random UUID similar to this: `eeccb8c5-9943-b2bb-bb5e-222f4e14b687`. |
| **Example** | `uuid()` |
| **Result** | various |
#### `version()`
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| **Description** | Return the currently active version of DuckDB in this format. |
| **Example** | `version()` |
| **Result** | various |
## Utility Table Functions
A table function is used in place of a table in a `FROM` clause.
| Name | Description |
|:--|:-------|
| [`glob(search_path)`](#globsearch_path) | Return filenames found at the location indicated by the *search_path* in a single column named `file`. The *search_path* may contain [glob pattern matching syntax]({% link docs/stable/sql/functions/pattern_matching.md %}). |
| [`repeat_row(varargs, num_rows)`](#repeat_rowvarargs-num_rows) | Returns a table with `num_rows` rows, each containing the fields defined in `varargs`. |
#### `glob(search_path)`
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| **Description** | Return filenames found at the location indicated by the *search_path* in a single column named `file`. The *search_path* may contain [glob pattern matching syntax]({% link docs/stable/sql/functions/pattern_matching.md %}). |
| **Example** | `glob('*')` |
| **Result** | (table of filenames) |
#### `repeat_row(varargs, num_rows)`
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| **Description** | Returns a table with `num_rows` rows, each containing the fields defined in `varargs`. |
| **Example** | `repeat_row(1, 2, 'foo', num_rows = 3)` |
| **Result** | 3 rows of `1, 2, 'foo'` |