本文介绍了在 SQLite 中声明变量并使用它的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我想在 SQLite 中声明一个变量并在 insert 操作中使用它.
I want to declare a variable in SQLite and use it in insert operation.
就像在 MS SQL 中一样:
Like in MS SQL:
declare @name as varchar(10)
set name = 'name'
select * from table where name = @name
例如，我需要获取 last_insert_row 并在 insert 中使用它.
For example, I will need to get last_insert_row and use it in insert.
我发现了一些关于绑定的东西，但我并没有完全理解它.
I have found something about binding but I didn't really fully understood it.
推荐答案
SQLite 不支持本机变量语法，但您可以使用内存中的临时表实现几乎相同的效果.
SQLite doesn't support native variable syntax, but you can achieve virtually the same using an in-memory temp table.
我已经在大型项目中使用了以下方法并且效果很好.
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;
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