官术网_书友最值得收藏!

Editing database objects – putting context menus to work

Each object in the Connections navigator has a context menu associated with it. Each context menu invokes a dialog that supports SQL commands that range from a single, simple command (such as DROP TABLE HR.COUNTRIES) to a collection of basic and complex commands. Throughout the chapter, we have stated that any of the activities that we're performing uses a UI as an interface for the underlying SQL command. Certainly, typing the drop table command is faster than selecting the items and invoking the dialog, assuming of course that you know the syntax. In this section, we'll briefly single out a few of these context menus.

Editing objects

Each of the Create dialogs has a matching Edit dialog. Most of the Edit dialogs directly match the object's Create dialog. If you invoke any Edit dialog, the DDL tab or node is initially empty, as it was when you first invoked the Create dialog. As soon as you change any of the properties, the DDL tab or node is populated with the SQL to reflect the changes. For many objects, such as triggers or views, editing the object results in a Create or Replace… command. For other objects, such as Sequences or Tables, editing the objects results in an Alter… command.

Consider the Edit Table dialog as shown in the following screenshot. The dialog is in the form of the advanced Create table dialog. Notice that you can no longer switch the table type nor create partitions. While you can certainly add or delete columns, you cannot reorder them (unless you drop and recreate them). You'll find that other database rules, such as reducing the column width, are also enforced if the column already contains data.

主站蜘蛛池模板: 浦江县| 安义县| 寻甸| 曲周县| 洞头县| 普兰县| 山阴县| 兴宁市| 会泽县| 鲁甸县| 丰都县| 金门县| 天津市| 黑河市| 石泉县| 湖口县| 客服| 河南省| 玉环县| 九龙县| 安宁市| 巫山县| 巫溪县| 资阳市| 惠水县| 沂源县| 天柱县| 大余县| 姜堰市| 福鼎市| 台北市| 吉木萨尔县| 克山县| 呼玛县| 江口县| 达拉特旗| 丰宁| 密云县| 津市市| 青河县| 莆田市|