Array Functions
array_append(anyarray, anyelement)
Description: Appends an element to the end of an array, and only supports dimension-1 arrays.
Return type: anyarray
Example:
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SELECT array_append(ARRAY[1,2], 3) AS RESULT; result --------- {1,2,3} (1 row) |
array_prepend(anyelement, anyarray)
Description: Appends an element to the beginning of an array, and only supports dimension-1 arrays.
Return type: anyarray
Example:
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SELECT array_prepend(1, ARRAY[2,3]) AS RESULT; result --------- {1,2,3} (1 row) |
array_cat(anyarray, anyarray)
Description: Concatenates two arrays, and supports multi-dimensional arrays.
Return type: anyarray
Example:
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SELECT array_cat(ARRAY[1,2,3], ARRAY[4,5]) AS RESULT; result ------------- {1,2,3,4,5} (1 row) SELECT array_cat(ARRAY[[1,2],[4,5]], ARRAY[6,7]) AS RESULT; result --------------------- {{1,2},{4,5},{6,7}} (1 row) |
array_ndims(anyarray)
Description: Returns the number of dimensions of the array.
Return type: int
Example:
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SELECT array_ndims(ARRAY[[1,2,3], [4,5,6]]) AS RESULT; result -------- 2 (1 row) |
array_dims(anyarray)
Description: Returns a text representation of array's dimensions.
Return type: text
Example:
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SELECT array_dims(ARRAY[[1,2,3], [4,5,6]]) AS RESULT; result ------------ [1:2][1:3] (1 row) |
array_length(anyarray, int)
Description: Returns the length of the requested array dimension.
Return type: int
Example:
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SELECT array_length(array[1,2,3], 1) AS RESULT; result -------- 3 (1 row) |
array_lower(anyarray, int)
Description: Returns lower bound of the requested array dimension.
Return type: int
Example:
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SELECT array_lower('[0:2]={1,2,3}'::int[], 1) AS RESULT; result -------- 0 (1 row) |
array_upper(anyarray, int)
Description: Returns upper bound of the requested array dimension.
Return type: int
Example:
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SELECT array_upper(ARRAY[1,8,3,7], 1) AS RESULT; result -------- 4 (1 row) |
array_to_string(anyarray, text [, text])
Description: Uses the first text as the new delimiter and the second text to replace NULL values.
Return type: text
Example:
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SELECT array_to_string(ARRAY[1, 2, 3, NULL, 5], ',', '*') AS RESULT; result ----------- 1,2,3,*,5 (1 row) |
In array_to_string, if the null-string parameter is omitted or NULL, any null elements in the array are simply skipped and not represented in the output string.
string_to_array(text, text [, text])
Description: Uses the second text as the new delimiter and the third text as the substring to be replaced by NULL values. A substring can be replaced by NULL values only when it is the same as the third text.
Return type: text[]
Example:
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SELECT string_to_array('xx~^~yy~^~zz', '~^~', 'yy') AS RESULT; result -------------- {xx,NULL,zz} (1 row) SELECT string_to_array('xx~^~yy~^~zz', '~^~', 'y') AS RESULT; result ------------ {xx,yy,zz} (1 row) |
- In string_to_array, if the delimiter parameter is NULL, each character in the input string will become a separate element in the resulting array. If the delimiter is an empty string, then the entire input string is returned as a one-element array. Otherwise the input string is split at each occurrence of the delimiter string.
- In string_to_array, if the null-string parameter is omitted or NULL, none of the substrings of the input will be replaced by NULL.
unnest(anyarray)
Description: Expands an array to a set of rows.
Return type: setof anyelement
Example:
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SELECT unnest(ARRAY[1,2]) AS RESULT; result -------- 1 2 (2 rows) |
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