Dictionary A CREATE INDEX command has the following syntax:The only required elements are the CREATE INDEX command, the name of the index, the ON argument, the name of the table that contains the fields that you want to index, and the list of fields to be included in the index.The DESC argument causes the index to be created in descending order, which can be useful if you frequently run queries that look for top values for the indexed field, or that sort the indexed field in descending order. ข้อมูล… What is the abbreviation for Data-Definition-Language? in Chinese (Traditional) Also suppose that you frequently forget to input a value for the car's condition, and that you always want to record this information.
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By default, an index is created in ascending order.The WITH PRIMARY argument establishes the indexed field or fields as the primary key of the table.The WITH DISALLOW NULL argument causes the index to require that a value be entered for the indexed field — that is, null values are not allowed.Suppose that you have a table named Cars with fields that store the name, year, price, and condition of used cars that you are considering for purchase. Your feedback will be reviewed. 'pa pdd chac-sb tc-bd bw hbr-20 hbss lpt-25' : 'hdn'">
in Korean in Chinese (Simplified) You could create a UNIQUE constraint that applies to these fields, by using the following procedure:The design grid is hidden, and the SQL view object tab is displayed.ADD COLUMN field type[(size)] [NOT NULL] [CONSTRAINT constraint] {{#verifyErrors}}
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in Italian This article explains data-definition queries and how to use them to create tables, constraints, indexes, and relationships.
A data definition language or data description language (DDL) is a syntax similar to a computer programming language for defining data structures, especially database schemas.
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You can do the following:The design grid is hidden, and the SQL view object tab is displayed.To create an index on an existing table, you use a CREATE INDEX command. Learn more. in Malay The word in the example sentence does not match the entry word. données… Use the Generate DDL wizard to export data objects from a database or a data model to a DDL script. in Norwegian The sentence contains offensive content. data definition: 1. information, especially facts or numbers, collected to be examined and considered and used to….
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Also suppose that the table has become large and that you frequently include the year field in queries. Suppose that you want to make sure that no two records in the Cars table have the same set of values for Name, Year, Condition, and Price.