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Previous Page: sort the data in the reverse order, select only the first {rows} rows, where the {unique_key} is less than {first_val} (the value of the {unique_key} of the first row in the current page), and sort the result in the correct order; Read and send to display all the rows read from the database
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.
Firebird has the same syntax in Data Modification Language statements (DSQL); the statement may add at most one row. [2] In stored procedures, triggers and execution blocks (PSQL) the aforementioned Oracle syntax is used. [3]
A common table expression, or CTE, (in SQL) is a temporary named result set, derived from a simple query and defined within the execution scope of a SELECT, INSERT, UPDATE, or DELETE statement.
A cursor is a pointer to a private SQL area that stores information coming from a SELECT or data manipulation language (DML) statement (INSERT, UPDATE, DELETE, or MERGE). A cursor holds the rows (one or more) returned by a SQL statement. The set of rows the cursor holds is referred to as the active set. [12] A cursor can be explicit or implicit ...
Before code can access the data, it must open the cursor with the OPEN statement. Directly following a successful opening, the cursor is positioned before the first row in the result set. OPEN cursor_name. Applications position cursors on a specific row in the result set with the FETCH statement. A fetch operation transfers the data of the row ...
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.
In relational databases a virtual column is a table column whose value(s) is automatically computed using other columns values, or another deterministic expression. Virtual columns are defined of SQL:2003 as Generated Column, [1] and are only implemented by some DBMSs, like MariaDB, SQL Server, Oracle, PostgreSQL, SQLite and Firebird (database server) (COMPUTED BY syntax).