Return true when the input string begins with the given prefix, false otherwise.
STARTS_WITH(str, prefix)## Overview Returns true when the input string begins with the given prefix, and false otherwise. STARTS_WITH (underscore form) is the common SQL name; STARTSWITH (no underscore) is an equivalent alias. The match is literal and case-sensitive; for pattern-based prefix matching use LIKE 'prefix%'. Prefix tests are natural fits for partitioning namespaces (URLs, file paths, identifier codes) and for dispatching rows into category buckets based on a known-length leading code. ## Behavior - Returns NULL when either argument is NULL. - Returns true for an empty prefix: the empty string is a prefix of every string. - Returns false when the prefix is longer than the input string. - The match is case-sensitive and literal; SQL wildcards and regex metacharacters are treated as ordinary characters. - Operates on Unicode code points; multi-byte UTF-8 characters are matched correctly. - Short-circuits on the first mismatched character. ## Compatibility - Semantically equivalent to str LIKE prefix || '%' after wildcard escaping. - Semantically equivalent to LEFT(str, LENGTH(prefix)) = prefix for non-NULL inputs.
| Name | Type | Description |
|---|---|---|
str | Specifies the input string to test. | |
prefix | Specifies the prefix to check for. The match is case-sensitive and literal. |
-- Matching prefix
SELECT STARTS_WITH('hello world', 'hello'); -- true-- Non-matching prefix
SELECT STARTS_WITH('hello world', 'world'); -- false-- Case-sensitive
SELECT STARTS_WITH('Hello', 'hello'); -- false-- Empty prefix always matches
SELECT STARTS_WITH('hello', ''); -- true-- NULL propagates
SELECT STARTS_WITH(CAST(NULL AS VARCHAR), 'x'); -- NULL-- Filter URLs by protocol
SELECT url
FROM ops.etl.staging_links
WHERE STARTS_WITH(url, 'https://');