Visual FoxPro uses the default value if you use the SQL ALTER TABLEcommand to remove autoincrementing for the field. PRIMARY KEY | UNIQUE PRIMARY KEY creates a primary index for the field specified in FieldName1. UNIQUE creates a candidate index for the field specified in FieldName1. The ...
If you use theAUTOINCclause to turn on autoincrementing for a field and specify a default value, Visual FoxPro stores the default value in the table but does not use it. Visual FoxPro uses the default value if you use the SQLALTER TABLEcommand to remove autoincrementing for the field. ...
Visual FoxPro uses the default value if you use the ALTER TABLE - SQL command to remove autoincrementing for the field. PRIMARY KEY | UNIQUE PRIMARY KEY creates a primary index for the field specified in FieldName1. UNIQUE creates a candidate index for the field specified in FieldName1. ...
MySqlCommand:执行一条sql语句。 MySqlDataReader: 包含sql语句执行的结果,并提供一个方法从结果中阅读一行。...MySqlHelper: Helper class that makes it easier to work with the provider. 1.添加动态链接库文件 方法一:Visual Studio...方法二:安装数据库MySQL时要选中Connector.NET 6.9的安装,将C:\Program ...
1、创建包含sql命令的sql脚本文件 文件中包含一些列的sql语句,每条语句最后以;结尾,文件内容示例如下: --创建表,使用“--”进行注释 create table 表名称 ( Guid Varchar(38) not null primary key, Title Varchar(255), ) TYPE=InnoDB; --在表A中增加字段Status ...
create table v1(c1 varchar, c2 varchar(2), c3 varchar(4)); 1.1 varchar语法解析 varchar和varchar(2)的区别主要是在: TypeName->typmods链表会挂一个A_Const记录括号内给的长度。 1.2 varchar语义解析 transform函数不会处理建表时的varchar类型,语义解析生成的Query树结构: ...
1.使用pl/sql代码实现,但要求你组合后的长度不能超出oracle varchar2长度的限制 create or replace type strings_table is table of varchar2(20); / create or replace function merge (pv in strings_table) return varchar2 is ls varchar2(4000); begin for i in 1..pv.count loop ls := ls || ...
1) copy status_var to global_status_var; 2) reset_system_status_vars 3) THD::init 4) THD::cleanup: MDL_context_backup_manager::create_backup; transaction_cache_detach{create_and_insert_new_transaction}; trans_rollback; transaction_cache_delete;mysql_ha_cleanup[clean up handler's table];...
ExecuteToStreamでは、InvalidOperationExceptionをスローします。 XmlCommandType = OracleXmlCommandType.Query ExecuteToStreamでは、CommandTextプロパティの選択文を実行し、成功した場合は指定したStreamに生成されたXML文書を追加します。 SQL問合せによって行が戻されない場合は、指定されたStreamには何も追加...
Specifies where the trace output is to be recorded. You can use more than one value, but do not use the same value twice. If you do not specify a value, the trace output is sent to the default destination shown in the following table. If the specified destination is not active or ...