SQL - Select command summary 1 of 2

Select ... From

Tells the database what fields (columns) you want to retrieve from and from where (which tables).
One or more tables can be selected (using join)
Multiple columns are separated by commas, and column names include the table.
An * will select all columns
Field names with spaces need to be surrounded by brackets (Client Details) - though spaces are not recommended when building tables.
You can specify your own headings (alias) using the AS keyword.
Arithmetic can be included as part of the select
Examples
- Select * from employees;
- Select Employees.LastName, FirstName, Id From Employees;
- Select (Order Details), (Discount Amount), Order.(Order Id) From (Order Details), Orders;
- Select LastName As Sunname From Employeees
- Select e.FirstName, e.LastName From Employees e;
- Select SellPrice - Cost As Profit From Orders;
- Select Title +' '+FirstName +' '+ LastName From Employees;

Used to filter rows
Columns in the where clause do not necessarily have to appear in the Select clause.
Expressions may include; =, > , < , >=, <=, != or <> (not equal to),Between (for ranges), Like (for masks), In (for lists), Exists (used for embedded subqueries to see whether any rows were returned)
Statements may be linked with And, Or , Not.
Examples
- Select * From Employees Where Employees.Salary > 50000;
- Select * From Employees Where FirstName = "Tui" And (LastName = "Rangi" Or LastName = "Corich")
- Select * From Employees Where LastName In ("Smith","White","Rangi");
- Select * From Employees Where Lastame Like "M%";
  - Finds all LastNames starting with M.
  - Can have %m% for all values with an m in them
  - Use a _ (underscore) for a single character, eg. Ha_e for Hame, Hape, etc..
- Select FirstName, LastName Form Employees Where StartDate Between #01/01/98# And #31/09/98# And EmployeeType = "Sales";
- Select FirstName, LastName From Employees Where Exists (Select* From TimeSheets Where Date > #01/01/98#);
- Select CustCode, CustName From Customer Where Customer.CustCode IN (Select Accounts.AccCode From Accounts Where CreditStatus = "Hold");

Goups the selected rows.
If the table does not have an index defined the query may run slowly
Having filters out unwanted groups
Examples
- Select * From Timesheets Group by TsDate;
- Select * From Timesheets Group by TsDate Having TsDate Between #01/01/98# And #10/10/98#;