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91 lines
2.2 KiB
Markdown
91 lines
2.2 KiB
Markdown
---
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slug: /en/sql-reference/aggregate-functions/reference/groupconcat
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sidebar_position: 363
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sidebar_label: groupConcat
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title: groupConcat
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---
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Calculates a concatenated string from a group of strings, optionally separated by a delimiter, and optionally limited by a maximum number of elements.
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**Syntax**
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``` sql
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groupConcat(expression [, delimiter] [, limit]);
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```
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**Arguments**
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- `expression` — The expression or column name that outputs strings to be concatenated..
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- `delimiter` — A [string](../../../sql-reference/data-types/string.md) that will be used to separate concatenated values. This parameter is optional and defaults to an empty string if not specified.
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- `limit` — A positive [integer](../../../sql-reference/data-types/int-uint.md) specifying the maximum number of elements to concatenate. If more elements are present, excess elements are ignored. This parameter is optional.
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:::note
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If delimiter is specified without limit, it must be the first parameter following the expression. If both delimiter and limit are specified, delimiter must precede limit.
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:::
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**Returned value**
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- Returns a [string](../../../sql-reference/data-types/string.md) consisting of the concatenated values of the column or expression. If the group has no elements or only null elements, and the function does not specify a handling for only null values, the result is a nullable string with a null value.
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**Examples**
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Input table:
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``` text
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┌─id─┬─name─┐
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│ 1 │ John│
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│ 2 │ Jane│
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│ 3 │ Bob│
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└────┴──────┘
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```
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1. Basic usage without a delimiter:
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Query:
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``` sql
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SELECT groupConcat(Name) FROM Employees;
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```
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Result:
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``` text
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JohnJaneBob
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```
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This concatenates all names into one continuous string without any separator.
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2. Using comma as a delimiter:
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Query:
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``` sql
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SELECT groupConcat(Name, ', ', 2) FROM Employees;
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```
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Result:
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``` text
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John, Jane, Bob
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```
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This output shows the names separated by a comma followed by a space.
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3. Limiting the number of concatenated elements
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Query:
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``` sql
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SELECT groupConcat(Name, ', ', 2) FROM Employees;
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```
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Result:
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``` text
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John, Jane
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```
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This query limits the output to the first two names, even though there are more names in the table.
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