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A SELECT statement retrieves zero or more rows from one or more database tables or database views. In most applications, SELECT is the most commonly used data manipulation language (DML) command. As SQL is a declarative programming language, SELECT queries specify a result set, but do not specify how to calculate it.
A derived table is the use of referencing an SQL subquery in a FROM clause. Essentially, the derived table is a subquery that can be selected from or joined to. The derived table functionality allows the user to reference the subquery as a table. The derived table is sometimes referred to as an inline view or a subselect.
After migrating the data and queries to SQL Server, the Access database can be linked to the SQL database, subject to data type conversion limitations: "Yes/No" types: In Microsoft Access there are three states for the Yes/No (True/False) data type: empty, no/false (0) and yes/true (−1).
Some basic steps are required in order to be able to access and manipulate data using ADO : Create a connection object to connect to the database. Create a recordset object in order to receive data in. Open the connection; Populate the recordset by opening it and passing the desired table name or SQL statement as a parameter to open function.
Since the Leszynski naming convention is a special form of Hungarian notation the same general advantages also apply to the Leszynski convention.. The use of distinctive prefixes makes your database self-documenting; when you see frmSales in VBA code, you will know that it references a form, and when you see curSales you will know that it is a Currency variable.
In version 3.5 it was able to bypass the Jet engine all together and directly access ODBC data sources, including Microsoft SQL Server and other enterprise database systems. DAO 3.6 shipped with Jet 4.0. Access 2007 and later uses ACE with its ACEDAO, where most new features supported by ACE are added to. ACEDAO no longer supports ODBCDirect.
In addition, aliasing is required when doing self joins (i.e. joining a table with itself.) In SQL, you can alias tables and columns. A table alias is called a correlation name, according to the SQL standard. [1] A programmer can use an alias to temporarily assign another name to a table or column for the duration of the current SELECT query ...
A table (called the referencing table) can refer to a column (or a group of columns) in another table (the referenced table) by using a foreign key. The referenced column(s) in the referenced table must be under a unique constraint, such as a primary key. Also, self-references are possible (not fully implemented in MS SQL Server though [5]).