Delete empty records in Access lexicon_PHP tutorial

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Use zero-length characters to indicate non-existence of data
If you want to indicate that data does not exist in a Microsoft Access database, you can Enter a zero-length string in the Text or Memo field (Zero-length string: A string containing no characters. You can use a zero-length string to indicate that you know the field has no value. To enter a zero-length string, Type two double quotation marks (" ") with no spaces between them. In a Microsoft Access project that connects to a Microsoft SQL Server database (Microsoft Access project: An Access file that connects to a Microsoft SQL Server database and is used to create client/server applications. The project file does not contain any data or objects based on data definitions (such as table or view). ), you can specify ). ) Enter a zero-length string into a varchar or nvarchar field.
Open a datasheet (Datasheet view: A window that displays data from a table, form, query, view, or stored procedure in row and column format. In Datasheet view, you can edit fields, add and delete data, and Search for data. ), or in Form view (Form view: A window that displays a form to display or accept data. Form view is the primary way to add and modify data in a table. In this view You can also change the form's design in ).

To enter a zero-length string in a field, type double quotation marks (" ") without spaces between them.

Even though the double quotes disappear when moved to other fields or objects, the field remains a zero-length string.
Difference between Null values ​​and zero-length strings (MDB)
/*Note The information in this topic applies only to Microsoft Access databases (.mdb). */
When viewing values ​​containing Null (Null: can be entered in fields or used in expressions and queries to indicate missing or unknown data. In Visual Basic, the Null keyword represents a Null value. Some fields (such as primary keys fields) may not contain Null values. ) values ​​and zero-length strings (Zero-length strings: A string containing no characters. You can use a zero-length string to indicate that you know the field has no value. Ways to Enter a Zero-Length String When you type two double quotes (" ") with no spaces between each other, the fields appear to be the same and have no value. But you can use an expression (an expression: any combination of arithmetic or logical operators, constants, function and field names, controls, and properties that evaluates to a single value. An expression can perform calculations, manipulate characters, or test data.) Null values ​​and zero-length strings.
In "Design" view ("Design" view: a window that displays the design of database objects (including: tables, queries, forms, macros, and data access pages). In "Design" view, you can create new database objects and modify Open a form, report, or data access page in the design of an existing database object.

http://www.bkjia.com/PHPjc/631232.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/631232.htmlTechArticleAuthor: Taote.com Source: Taote.com Note: Please indicate the source when reprinting. Use zero-length characters to indicate non-existence. Data To indicate that data does not exist in a Microsoft Access database, you can add it in "text...