Return first N characters of string

I need to select a shortened version of a field from a SQL Server table to use in a drop down list.

This field has to be limited to twenty characters. If the field has more than twenty characters, it should display the first twenty; if it has开发者_如何学C less than twenty characters, it should display the whole string.

How do I do this?

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Try left(sting_field,20) or right(sting_field,20)

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This SELECT should do:

SELECT 
  SUBSTRING(ISNULL(stringfield, ''), 1, 20)

It will replace a "NULL" value with an empty string '' and limit length to 20 chars max.

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You can use the LEFT command.

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I am confused... why dont you have the code that populates the dropdown manage the length of the data being loaded.

If you must do it within a query you could simply do a substring on the column:

https://learn.microsoft.com/en-us/sql/t-sql/functions/substring-transact-sql