QSqlQuery dropColumnQuery; dropColumnQuery.exec(dropColumnSql); qDebug()<<sql; qDebug()<<dropColumnSql; } } // 构建删除列的数据SQL语句(没试过,效果未知,记录一下,因为这是删除列名) QString sql = QString("DELETE FROM task_info WHERE %1 = 'some value'").arg(columnName); ...
INSERT INTO first_table_name [(column1, column2, ... columnN)] SELECT column1, column2, ...columnN FROM second_table_name [WHERE condition]; 您暂时可以先跳过上面的语句,可以先学习后面章节中介绍的 SELECT 和 WHERE 子句。 SQLite Delete 语句 SQLite 的DELETE查询用于删除表中已有的记录。可以使用...
C#複製 [Table("user")]publicclassUser{// PrimaryKey is typically numeric[PrimaryKey, AutoIncrement, Column("_id")]publicintId {get;set; } [MaxLength(250), Unique]publicstringUsername {get;set; } ... } 定義C# 類別之後,請呼叫SQLiteConnection類別上的CreateTable泛型方法,以在資料庫中產生資料...
SQLite DELETE 语句: DELETE FROM table_name WHERE{CONDITION}; SQLite DETACH DATABASE 语句: DETACH DATABASE'Alias-Name'; SQLite DISTINCT 子句: SELECT DISTINCT column1,column2...columnN FROM table_name; SQLite DROP INDEX 语句: DROP INDEX database_name.index_name; SQLite...
For example, suppose you have a table named "t1" with columns names "a", "b", and "c" and that you want to delete column "c" from this table. The following steps illustrate how this could be done: BEGIN TRANSACTION; CREATE TEMPORARY TABLE t1_backup(a,b); ...
sqlite>deletefromtb_task; sqlite>updatesqlite_sequencesetseq=0wherename='tb_task'; 查询所有表的自增列的序号值(seq字段为当前自增列的序号值,name字段为数据表名称) 1 2 3 sqlite> .headeron sqlite> .modecolumn sqlite>select*fromsqlite_sequence;...
1. Add a NOT NULL constraint to the column to beremoved. 2. Delete all rows from the table. 3. Drop the column using the ALTER TABLE statement. Method 3: Use a Trigger to Prevent Inserts with Null Values. 1. Create a trigger that fires on INSERT statements. 2. In the trigger, che...
sqlite> delete from tb_task; sqlite> update sqlite_sequence set seq=0 where name='tb_task'; 1. 2. 查询所有表的自增列的序号值(seq字段为当前自增列的序号值,name字段为数据表名称) sqlite> .header on sqlite> .mode column sqlite> select * from sqlite_sequence; ...
DELETE FROM table_name WHERE some_column=some_value;将小明这条记录删除:delete from student where name=”小明”;特点优势 SQLite作为一种嵌入式关系型数据库管理系统，由D. Richard Hipp于2000年设计和开发的，其设计目标是提供一个轻量级的、自包含的数据库引擎，可以在各种平台上无缝运行。主要有以下几个特点...
使用ContentResolver调用ContentProvider的delete()方法的示例代码如下: 代码语言:txt 复制 // 调用ContentProvider的delete()方法 Uri uri = Uri.parse("content://com.example.mycontentprovider/mytable"); String selection = "column1 = ?"; String[] selectionArgs = {"value1"}; int rowsDeleted = get...