Question

I want to write similar to “click for more”.

I cant remember this tech. I could via sql query.
I want to select data’s first 30 character.

How?

Answer 1

Every SQL flavor I’ve worked with has a substring function:

Oracle, MySQL, PostgreSQL, SQLite:

SELECT SUBSTR(column, 1, 30) FROM table;

SQL Server, MySQL:

SELECT SUBSTRING(column, 1, 30) FROM table;

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Alternatively, you can make use of the LEFT function, which is supported by some of these DBs:

MySQL, SQL Server:

SELECT LEFT(column, 30) FROM table;

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And of course you can use a column alias, like:

SELECT SUBSTR(column, 1, 30) AS partial FROM table;
SELECT SUBSTRING(column, 1, 30) AS partial FROM table;