The SUBSTR function in SQL is used to extract a substring from a given string starting at a specified position for a specified length.

? Syntax

SUBSTR(string, start_position, length)

• string: The source string.

• start_position: The position to start extracting (1-based index).

• length (optional): Number of characters to extract. If omitted, extracts till the end of the string.

? Return

• Returns a substring starting from start_position.

• If length is provided, returns that many characters; otherwise, returns to the end.

? Examples

SELECT SUBSTR('OpenAI ChatGPT', 1, 6) AS Substring1;  -- Returns 'OpenAI'SELECT SUBSTR('OpenAI ChatGPT', 8) AS Substring2;     -- Returns 'ChatGPT'SELECT SUBSTR('OpenAI ChatGPT', 5, 10) AS Substring3; -- Returns 'AI ChatGPT'

? Notes

• In some SQL dialects, the function is named SUBSTRING() but usage is similar.

• start_position is usually 1-based (first character is position 1).

• Negative start_position values may count from the end in some databases (e.g., Oracle).

Dialect Differences

If you want, I can also provide equivalent examples for your specific SQL dialect!