What is the purpose of the SQL LEFT function?

1 year ago
Benjamin Taylor
1 minute

The LEFT function in SQL is used to return a specified length portion of the left side of a string.

Syntax: LEFT(string, length)

Explanation of parameters:

  1. String: the string to be trimmed.
  2. length: length of the string to be returned.

Points to consider:

  1. Return the entire string if the value of ‘length’ is greater than the length of the string.
  2. If the value of length is 0 or negative, return an empty string.
  3. If string is NULL, then return NULL.

原文： 我需要一个更有挑战性的工作，这份工作对我来说太容易了。
重述：I need a more challenging job. This job is too easy for me.

SELECT LEFT('Hello World', 5) AS Result;

The output is:

Hello

In the example above, the LEFT function will return the leftmost 5 characters of the string ‘Hello World’, which is ‘Hello’.

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