SQL: List of the first letters of column value?

I have keywords in table (for example texts tab开发者_Python百科le, key column). How to get list of first letters of keys ?

      key
[b]utton.upload
[b]utton.upload_file
[c]ontent.policy
[d]ontent.policy

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try

SUBSTRING (my_column, 1, 1)

or

SELECT LEFT(my_column,1)

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I agree with the previous response.

But for the full query:

SELECT substring(key,1,1) AS FirstLetter FROM texts

Frank