Inserting and Querying Data in Tables

Inserting and Querying Data in Tables

To insert or add a row of data to a table, use the insert statement.

To insert records into a table, enter the key phrases, followed by the table name, an open parenthesis, a list of column names separated by commas, a closing parenthesis, the keyword values, and a list of values contained in parentheses. The values you input will be stored in rows and will correspond to the column names you choose. Numbers should not be encased in single quotations, but strings should be.

• Put values (first column, last column) into “table name” (first column, last column).

Use the SQL SELECT query to select all the data from a table.

• Before you can query data from a table, you must first know which table you wish to query. Following that, you may specify the table name from the FROM clause.

To choose a subset of columns in a table, use the SELECT command.

• In practice, it is unusual to obtain data from all the columns in a table. In fact, just a subset of columns is required. You must provide the columns in the SELECT clause to do this.
• The following query employs the SELECT statement to retrieve all of the last names from the worker’s table’s last name field.

Using the SQL SELECT command in conjunction with additional components

• In addition to table columns, the following components can be used in the SELECT clause:

1. Numbers or Strings
2. Expressions
3. SQL operations
4. A user-defined function
5. The following query, for example, uses the SELECT statement in conjunction with a basic expression.

Summary

• To query data from a table, use the SELECT command.
• After the SELECT clause to which you wish to query data, specify one or more column names.
• Enter the name of the table from which you wish to get data.