sue queries in Structured Query Language (SQL). SQL is a simple language that specifies the syntax for constructing a search request and controlling how the results are returned. There are some variations in syntax and capabilities among database vendors, but the basic commands are generally compatible among databases. An SQL query specifies what information you are interested in and what table it can be found in. One of the most fundamental SQL commands is SELECT, which retrieves a set of information from a table. The * character means to include results from every column in the table. The WHERE clause selects a single record from the table and looks for a particular value in a particular field. INSERT allows data to be added by adding rows to a table. The DELETE command is used to remove rows from a table that match a specified condition. Since relational databases are beneficial in their way to establish relationships among the various tables, data can be stored in separate but interrelated tables rather than trying to put it all into one table. The use of a unique key in each table can also make database access faster and more efficient. When the database expects queries based on the contents of a particular column, it can optimize its internal index files appropriately. ...
