![]() Move Cursor to next row and fetch into a record variable (rowvar was declared in the DECLARE section) RAISE NOTICE 'Name = %, Job=%', item.last_name, item.job_id UPDATE employee SET salary = salary*1.2 WHERE CURRENT OF c3 Įxample of Use an Implicit Cursor (FOR Loop Over Queries) DO $$ There are restrictions on what the cursor’s query can select for this type of DML to succeed.įor example, the current row to which the C3 cursor is pointed to is updated. When a cursor is positioned on a table row, that row can be updated or deleted. Move to the last row (null or no data found) for cursor c3. The special variable FOUND can be checked to determine if there is a next row. MOVE repositions a cursor without retrieving any data and works such as the FETCH command, except it only repositions the cursor in the dataset and doesn’t return the row to which the cursor is moved. DO $$Įxample of Move a Cursor Without Fetching Data The following PL/pgSQL code uses a loop to fetch all rows from the cursor and then exit after the last record is fetched (using EXIT WHEN NOT FOUND). PL/pgSQL supports detecting when a cursor has no more data to return and can be combined with loops to iterate over all rows of a cursor reference. DO $$įETCH LAST FROM c3 INTO emp_id, emp_name įor more information, see FETCH in the PostgreSQL documentation.Ĭlose a PL/pgSQL cursor using the CLOSE command. For example, fetch the last row from the cursor into the declared variables. Omitting direction is equivalent to as specifying NEXT. PL/pgSQL supports a special direction clause when fetching data from a cursor using the NEXT, PRIOR, FIRST, LAST, ABSOLUTE count, RELATIVE count, FORWARD, or BACKWARD arguments. DO $$Ĭ3 CURSOR FOR SELECT id, name FROM employees DO $$įetch the values returned from the c3 cursor into two scalar datatypes. Fetch the values returned from the c3 cursor into a row variable. The PL/pgSQL FETCH command retrieves the next row from the cursor into a variable. DO $$Ĭ3 CURSOR FOR SELECT * FROM employees where id = var1 If the cursor was not declared to take arguments, the arguments can be specified outside the cursor. DO $$Ĭ3 CURSOR (var1 integer) FOR SELECT * FROM employees where id = var1 įor the c3 cursor, supply the argument value expressions. Open a cursor that was bound to a query when the cursor was declared and that was declared to take arguments. The comparison value for col1 is inserted using a USING parameter. For example, the table name is inserted into the query using format(). ![]() Parameter values can be inserted into the dynamic command using format() and USING. OPEN c1 FOR EXECUTE format('SELECT * FROM %I WHERE col1 = $1',tabname) USING keyvalue This approach provides greater flexibility. Open a cursor variable that was declared as Unbound and specify the query to run as a string expression. OPEN c1 FOR SELECT * FROM employees WHERE id = emp_id Open a Cursor variable that was declared as Unbound and specify the query to run. NO SCROLL specifies that rows can’t be retrieved backwards.ĭepending upon the complexity of the run plan for the query, SCROLL might create performance issues.īackward fetches aren’t allowed when the query includes FOR UPDATE or FOR SHARE. SCROLL specifies that rows can be retrieved backwards. DECLARE c3 CURSOR (var1 integer) FOR SELECT * FROM employees where id = var1 Declare a cursor in PL/pgSQL to be used with any query. In the following example, you can replace FOR with IS for Oracle compatibility. ![]() DECLARE c2 CURSOR FOR SELECT * FROM employees The variable c1 is unbound since it isn’t bound to any particular query.ĭeclare a cursor in PL/pgSQL with a bound query. All access to cursors in PL/pgSQL is performed through cursor variables, which are always of the refcursor data type.Ĭreate a PL/pgSQL cursor by declaring it as a variable of type refcursor.ĭeclare a cursor in PL/pgSQL to be used with any query. ![]() They can encapsulate the query and read the query results a few rows at a time. Similar to Oracle PL/SQL cursors, PostgreSQL has PL/pgSQL cursors that enable you to iterate business logic on rows read from the database. (SELECT last_name, job_id FROM employees WHERE job_id LIKE '%MANAGER%'ĪND manager_id > 400 ORDER BY last_name) LOOPĭBMS_OUTPUT.PUT_LINE('Name = ' || item.last_name || ', Job = ' || item.job_id) įor more information, see Explicit Cursor Declaration and Definition and Implicit Cursor Attribute in the Oracle documentation. The cursor runs a query and stores values returned into a record.Ī loop iterates over the cursor data set and prints the result. Define an implicit PL/SQL cursor using a FOR Loop. ![]()
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