* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 5.02-Queries
Survey
Document related concepts
Open Database Connectivity wikipedia , lookup
Serializability wikipedia , lookup
Oracle Database wikipedia , lookup
Microsoft SQL Server wikipedia , lookup
Entity–attribute–value model wikipedia , lookup
Functional Database Model wikipedia , lookup
Relational algebra wikipedia , lookup
Microsoft Access wikipedia , lookup
Extensible Storage Engine wikipedia , lookup
Concurrency control wikipedia , lookup
Ingres (database) wikipedia , lookup
Microsoft Jet Database Engine wikipedia , lookup
Clusterpoint wikipedia , lookup
Versant Object Database wikipedia , lookup
Relational model wikipedia , lookup
Transcript
Queries Objective 5.02 Understand queries, forms, and reports used in business. Database Objects ► Objective 5.01 discussed and explained how tables are the building blocks for all databases. ► This objective will use tables to create three types of database objects: Queries Forms Reports 5.02 Understand database queries, forms, and reports used in business. Slide 2 Query ►A database object created by placing filters and selecting multiple criteria (comparison operators) to extract information from one or more tables 5.02 Understand database queries, forms, and reports used in business. Slide 3 Advantages of a Query ► Can be saved and used to perform other operations. ► One table can be associated with multiple queries. ► Can perform specialized operations For example, calculations can be performed on field values and the results can be placed in a new column of a datasheet. 5.02 Understand database queries, forms, and reports used in business. Slide 4 The Difference Between Queries and Filters ►A filter is a one-time deal. It allows application of a set of selection criteria and/or sorting instructions to the records in a table. It is a quick and temporary tool that is created for one-time use in the context of a particular table. ► A query is reusable. It allows the selection criteria and/or sorting instructions to be saved and reused. 5.02 Understand database queries, forms, and reports used in business. Slide 5 Comparison Operators for Queries and Filters Less Than or Equal To <= Less Than < Greater Than or Equal To >= Greater Than > Not Equal To <> Equal To = 5.02 Understand database queries, forms, and reports used in business. Slide 6 Conditional Operators for Queries and Filters ► The AND condition reduces the number of records because both conditions must be met. ► The OR condition increases the number of records because records are selected if either condition is met. 5.02 Understand database queries, forms, and reports used in business. Slide 7