Capabilities of theSELECTStatement(SELECT语句的功能) Data retrieval from data base is done through appropriate and efficient use of SQL. Three concepts from relational theory encompass the capability of the SELECT statement: projection, selection, and joining. Projection(投影): A project operation sele...
01 Writing Basic SQL SELECT Statements WritingBasicSQLSELECTStatements DatabaseProgramming CopyrightJetPro,2001.Allrightsreserved.Objectives Aftercompletingthislesson,youshouldbeabletodothefollowing:ListthecapabilitiesofSQLSELECTstatementsExecuteabasicSELECTstatement DatabaseProgramming 1-2CopyrightJetPro,2001.Allrights...
The expression of this statement is evaluated in such a way that an SQL SELECT statement is sent to the primary database engine. The result value of this expression must be a single value. If the variable is a row or record variable, the result value may be a row value. The variable ...
This statement is a basic query statement and is used to return the query results.The table to be queried must already exist, or an error message will be displayed.When s
No more than one SELECT statement can be used in a query that includes other SQL statements. Both simple and bracketed comments can be used in an SQL query. Simple comments are introduced with two consecutive hyphens (--) and end with the end of a line. Simple comments cannot be continued...
1. Using the same Select statement you have above, remove the ' ; ' and add where department_id = 100; Click F9. The Results tab shows fewer records returned. 4. Use SQL*Plus commands The SQL Worksheet allows you to use a selection of SQL*Plus commands. SQL*Plus commands have to be...
Basic SQL clauses: SELECT, FROM, and WHERE A SQL statement takes the general form: SELECT field_1 FROM table_1 WHERE criterion_1 ; Notes: Access ignores line breaks in a SQL statement. However, consider using a line for each clause to help improve the readability of your SQL...
<MailMergeObject>.OpenDataSource Name:="C:\MyDB.mdb", _ SQLStatement:="SELECT * FROM [MyTable]", _ SubType:=wdMergeSubTypeWord2000 自动化示例 以下示例代码通过使用 OLEDB (通过 ODSO) 创建和执行表单字母的邮件合并。 使用的数据源是示例 Access 数据库 Northwind.mdb。 如果未安装 Northwind,请启...
<MailMergeObject>.OpenDataSource Name:="C:\MyDB.mdb", _ SQLStatement:="SELECT * FROM [MyTable]", _ SubType:=wdMergeSubTypeWord2000 自动化示例 以下示例代码通过使用 OLEDB (通过 ODSO) 创建和执行表单字母的邮件合并。 使用的数据源是示例 Access 数据库 Northwind.mdb。 如果未安装...
有時候您的程式碼需要 Unmanaged 資源,例如檔案控制代碼、COM 包裝函式或 SQL 連線。 Using 區塊可確保當您的程式碼完成時,會處置一或多個此類資源。 這可讓其他程式碼使用這些資源。 .NET Framework 記憶體回收行程 (GC) 會處置 Managed 資源,而您無須額外進行編碼。 您不需要 Managed 資源的 Using 區塊。 不...