How Can I Simulate Variables in SQLite?

Mock variables in SQLite

SQLite itself does not natively support variables like other SQL dialects, but you can use in-memory temporary tables to emulate variable functionality. Here’s how to use it:

Step 1: Create a temporary variable table

<code class="language-sql">BEGIN; /* 开始事务 */

PRAGMA temp_store = 2; /* 使用内存模式创建临时表 */
CREATE TEMP TABLE _Variables(
  Name TEXT PRIMARY KEY,
  RealValue REAL,
  IntegerValue INTEGER,
  BlobValue BLOB,
  TextValue TEXT
);</code>

Step 2: Declare variables

<code class="language-sql">INSERT INTO _Variables (Name) VALUES ('VariableName');</code>

Step 3: Assign value

<code class="language-sql">UPDATE _Variables SET IntegerValue = ... WHERE Name = 'VariableName';</code>

Step 4: Get variable value

<code class="language-sql">... (
  SELECT COALESCE(RealValue, IntegerValue, BlobValue, TextValue)
  FROM _Variables
  WHERE Name = 'VariableName'
  LIMIT 1
) ...</code>

Step 5: Cleanup

<code class="language-sql">DROP TABLE _Variables;
END; /* 结束事务 */</code>

This method simulates the behavior of variables, allowing you to declare, assign and use variables in SQLite queries.

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