sql SQLite中缺少变量的一种相当普遍的解决方案。

Posted 2021-05-13

DROP TABLE IF EXISTS variables;
CREATE TEMP TABLE variables (
  name PRIMARY KEY NOT NULL,
  val_real REAL,
  val_integer INTEGER,
  val_blob BLOB,
  val_text TEXT);
  
-- Declare.
INSERT INTO variables (name) VALUES ('some_name');

-- Set.
UPDATE variables SET val_text = 'some_value' WHERE name = 'some_name' LIMIT 1;

-- Reference.
(SELECT coalesce(v.val_real, v.val_integer, v.val_blob, v.val_text)
  FROM variables v WHERE v.name = 'some_name')