| --- | |
| { | |
| "title": "REPEAT", | |
| "language": "en", | |
| "description": "The REPEAT function is used to repeat a specified string a specified number of times to generate a new string." | |
| } | |
| --- | |
| ## Description | |
| The REPEAT function is used to repeat a specified string a specified number of times to generate a new string. This function is commonly used for generating padding characters, creating separators, or generating test data. | |
| ## Syntax | |
| ```sql | |
| REPEAT(<str>, <count>) | |
| ``` | |
| ## Parameters | |
| | Parameter | Description | | |
| | -- | -- | | |
| | `<str>` | The source string to repeat. Type: VARCHAR | | |
| | `<count>` | The number of times to repeat, must be a non-negative integer. Type: INT | | |
| ## Return Value | |
| Returns VARCHAR type, representing the string repeated the specified number of times. | |
| Repeat rules: | |
| - When count is greater than 0, returns the result of str repeated count times | |
| - When count equals 0, returns an empty string | |
| - When count is less than 0, returns an empty string | |
| - If the resulting string is too long, it may be subject to string length limitations | |
| Special cases: | |
| - If any parameter is NULL, returns NULL | |
| - If str is an empty string, returns an empty string regardless of count | |
| - If count is 0, returns an empty string | |
| - If count is negative, returns an empty string | |
| ## Examples | |
| 1. Basic character repetition | |
| ```sql | |
| SELECT REPEAT('a', 3); | |
| ``` | |
| ```text | |
| +----------------+ | |
| | REPEAT('a', 3) | | |
| +----------------+ | |
| | aaa | | |
| +----------------+ | |
| ``` | |
| 2. Multi-character string repetition | |
| ```sql | |
| SELECT REPEAT('hello', 2); | |
| ``` | |
| ```text | |
| +--------------------+ | |
| | REPEAT('hello', 2) | | |
| +--------------------+ | |
| | hellohello | | |
| +--------------------+ | |
| ``` | |
| 3. Zero repetitions | |
| ```sql | |
| SELECT REPEAT('test', 0); | |
| ``` | |
| ```text | |
| +-------------------+ | |
| | REPEAT('test', 0) | | |
| +-------------------+ | |
| | | | |
| +-------------------+ | |
| ``` | |
| 4. Negative repetitions | |
| ```sql | |
| SELECT REPEAT('a', -1); | |
| ``` | |
| ```text | |
| +-----------------+ | |
| | REPEAT('a', -1) | | |
| +-----------------+ | |
| | | | |
| +-----------------+ | |
| ``` | |
| 5. NULL value handling | |
| ```sql | |
| SELECT REPEAT(NULL, 3), REPEAT('a', NULL); | |
| ``` | |
| ```text | |
| +------------------+-------------------+ | |
| | REPEAT(NULL, 3) | REPEAT('a', NULL) | | |
| +------------------+-------------------+ | |
| | NULL | NULL | | |
| +------------------+-------------------+ | |
| ``` | |
| 6. Empty string repetition | |
| ```sql | |
| SELECT REPEAT('', 5); | |
| ``` | |
| ```text | |
| +----------------+ | |
| | REPEAT('', 5) | | |
| +----------------+ | |
| | | | |
| +----------------+ | |
| ``` | |
| 7. Special character repetition | |
| ```sql | |
| SELECT REPEAT('-', 10), REPEAT('*', 5); | |
| ``` | |
| ```text | |
| +------------------+-----------------+ | |
| | REPEAT('-', 10) | REPEAT('*', 5) | | |
| +------------------+-----------------+ | |
| | ---------- | ***** | | |
| +------------------+-----------------+ | |
| ``` | |
| 8. UTF-8 character repetition | |
| ```sql | |
| SELECT REPEAT('ṭṛì', 3), REPEAT('ḍḍu', 2); | |
| ``` | |
| ```text | |
| +-------------------+-------------------+ | |
| | REPEAT('ṭṛì', 3) | REPEAT('ḍḍu', 2) | | |
| +-------------------+-------------------+ | |
| | ṭṛìṭṛìṭṛì | ḍḍuḍḍu | | |
| +-------------------+-------------------+ | |
| ``` | |
| 9. Mixed numbers and symbols | |
| ```sql | |
| SELECT REPEAT('123', 3), REPEAT('@#', 4); | |
| ``` | |
| ```text | |
| +-------------------+------------------+ | |
| | REPEAT('123', 3) | REPEAT('@#', 4) | | |
| +-------------------+------------------+ | |
| | 123123123 | @#@#@#@# | | |
| +-------------------+------------------+ | |
| ``` | |
| 10. UTF-8 character repetition | |
| ```sql | |
| SELECT REPEAT('ṭṛìṭṛì', 3); | |
| ``` | |
| ```text | |
| +--------------------------------------------------+ | |
| | REPEAT('ṭṛìṭṛì', 3) | | |
| +--------------------------------------------------+ | |
| | ṭṛìṭṛìṭṛìṭṛìṭṛìṭṛì | | |
| +--------------------------------------------------+ | |
| ``` | |