[SOLVED] Declare variable in SQLite and use it

Declare variable in SQLite and use it

I want to declare a variable in SQLite and use it in an insert operation.

MS SQL can use variables like this:

declare @name as varchar(10)
set name = 'name'
select * from table where name = @name

For example, I need to get last_insert_row and use it in insert.

I have found some info about binding, but I didn't fully understand it.

Solution

SQLite doesn't support native variable syntax, but you can achieve virtually the same using an in-memory temp table.

I've used the below approach for large projects and works like a charm.

    /* Create in-memory temp table for variables */
    BEGIN;

    PRAGMA temp_store = 2; /* 2 means use in-memory */
    CREATE TEMP TABLE _Variables(Name TEXT PRIMARY KEY, RealValue REAL, IntegerValue INTEGER, BlobValue BLOB, TextValue TEXT);

    /* Declaring a variable */
    INSERT INTO _Variables (Name) VALUES ('VariableName');

    /* Assigning a variable (pick the right storage class) */
    UPDATE _Variables SET IntegerValue = ... WHERE Name = 'VariableName';

    /* Getting variable value (use within expression) */
    ... (SELECT coalesce(RealValue, IntegerValue, BlobValue, TextValue) FROM _Variables WHERE Name = 'VariableName' LIMIT 1) ...

    DROP TABLE _Variables;
    END;