Find duplicates in SQL

If you have a primary key setup for the table, there can be no rows that have duplicate ID (Primary key column). Therefore you can’t find duplicates based on that column. 56 more words


Simplifies SQL-style Computations – In-group Computation

During developing the database applications, we often need to perform computations on the grouped data in each group. For example, list the names of the students who have published papers in each of the past three years; make statistics of the employees who have taken part in all previous training; select the top three days when each client gets the highest scores in a golf game; and the like. 614 more words


Simplifies SQL-style Computations – Relational Computation on Groups

During developing database applications, we are often faced with complicated SQL-style computations like relational computation on multilayered groups. As SQL requires summarizing during data grouping and it doesn’t support object-style relational access, it is difficult to deal with these computations. 1,101 more words


SELECT statement gotchas in Oracle and Sql Server

Here are some issues which may catch you out from time to time. In each case Sql Server and Oracle, or Oracle Sql and PL/Sql, or versions of Oracle, work differently. 701 more words

SQL Server