Thursday, 21 March 2013

Difference between MDX and T-SQL


i)                    The  ability of MDX  to reference multiple dimensions but SQL refers to only two dimensions, columns and rows when processing queries.

ii)                  In SQL, the SELECT clause is used to define the column layout for a query, while the WHERE clause is used to define the row layout. However, in MDX the SELECT clause can be used to define several axis dimensions, while the WHERE clause is used to restrict multidimensional data to a specific dimension or member.

iii)                The process of creating an SQL query is also different than that of creating an MDX query.

iv)                The visualization of an SQL result set is intuitive; the set is a two-dimensional grid of columns and rows. The visualization of an MDX result set is not as intuitive, however. Because a multidimensional result set can have more than three dimensions.

v)                  To refer to such two-dimensional data in SQL, the name of a column and the unique identification of a row, in whatever method is appropriate for the data, are used to refer to a single cell of data, called a field. However, MDX uses a very specific and uniform syntax to refer to cells of data, whether the data forms a single cell or a group of cells.