如何在SQLite中添加默认值？ [英] How to add default value in SQLite?

问题描述

  ALTER TABLE ITEM ADD COLUMN STATUS VARCHAR DEFAULT' N'; 
  

但是SQLite似乎没有添加N到创建的任何新ITEM的列。

我使用SQLite 3.6.22

解决方案

看起来不错。 这里是文档。

  sqlite>创建表t1（id INTEGER PRIMARY KEY，name TEXT，created DATE）; 
 sqlite> .table 
 t1 
 sqlite> .dump 
 PRAGMA foreign_keys = OFF; 
 BEGIN交易; 
 CREATE TABLE t1（id INTEGER PRIMARY KEY，name TEXT，created DATE）; 
 COMMIT; 
 
 sqlite> alter table t1 add column status varchar default'N'; 
 sqlite> .dump 
 PRAGMA foreign_keys = OFF; 
 BEGIN交易; 
 CREATE TABLE t1（id INTEGER PRIMARY KEY，name TEXT，created DATE，status varchar default'N'）; 
 COMMIT; 
 
 sqlite> insert into t1（name）values（test）; 
 sqlite> select * from t1; 
 1 | test || N 
  

转储模式并验证表明您的表结构在调用ALTER TABLE之后但在INSERT之前。如果是在事务中，请在插入之前>

。

$ sqlite3 test < .db.dump


I had a table modified to add status column to it in this fashion

ALTER TABLE ITEM ADD COLUMN STATUS VARCHAR DEFAULT 'N';

However SQLite doesnt seem to add N to the column for any new ITEM created. Is the syntax wrong or is there any issue with SQLite and its support for defaults.

I am using SQLite 3.6.22

解决方案

Looks good to me. Here are the Docs.

sqlite> create table t1 (id INTEGER PRIMARY KEY, name TEXT, created DATE);
sqlite> .table
t1
sqlite> .dump
PRAGMA foreign_keys=OFF;
BEGIN TRANSACTION;
CREATE TABLE t1 (id INTEGER PRIMARY KEY, name TEXT, created DATE);
COMMIT;

sqlite> alter table t1 add column status varchar default 'N';
sqlite> .dump
PRAGMA foreign_keys=OFF;
BEGIN TRANSACTION;
CREATE TABLE t1 (id INTEGER PRIMARY KEY, name TEXT, created DATE, status varchar default 'N');
COMMIT;

sqlite> insert into t1 (name) values ("test");
sqlite> select * from t1;
1|test||N

Dump your schema and verify that your table structure is there after calling ALTER TABLE but before the INSERT. If it's in a transaction, make sure to COMMIT the transaction before the insert.

$ sqlite3 test.db ".dump"

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