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With the same table, the query SELECT * FROM T WHERE C1 = 1 will result in all the elements of all the rows where the value of column C1 is '1' being shown – in relational algebra terms, a selection will be performed, because of the WHERE clause. This is also known as a Horizontal Partition, restricting rows output by a query according to ...
The set of rows the cursor holds is referred to as the active set. [12] A cursor can be explicit or implicit. In a FOR loop, an explicit cursor shall be used if the query will be reused, otherwise an implicit cursor is preferred. If using a cursor inside a loop, use a FETCH is recommended when needing to bulk collect or when needing dynamic SQL.
The FETCH FIRST clause specifies the number of rows to return. Some SQL databases instead have non-standard alternatives, e.g. LIMIT , TOP or ROWNUM . The clauses of a query have a particular order of execution, [ 5 ] which is denoted by the number on the right hand side.
With a non-scrollable (or forward-only) cursor, you can FETCH each row at most once, and the cursor automatically moves to the next row. After you fetch the last row, if you fetch again, you will put the cursor after the last row and get the following code: SQLSTATE 02000 (SQLCODE +100).
The DUAL table is a special one-row, one-column table present by default in Oracle and other database installations. In Oracle, the table has a single VARCHAR2(1) column called DUMMY that has a value of 'X'. It is suitable for use in selecting a pseudo column such as SYSDATE or USER.
1 / 6. 11 must-see astronomy events in 2025. The new year will be a busy one in the night sky with celestial sights of all types for everyone to enjoy, many of which can be viewed without needing ...
Unlike Oracle's earlier connect-by clause, recursive CTEs were designed with fixpoint semantics from the beginning. [1] Recursive CTEs from the standard were relatively close to the existing implementation in IBM DB2 version 2. [1]
The Perfect Scrambled Egg Method. I don't stray from my tried-and-true ratio, but have introduced two big changes: First, the splash of cream is replaced by a small splash of good olive oil.