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MERGE and TRUNCATE in SQL
SQL has two more table update operators, MERGE and TRUNCATE. MERGE, like INSERT, takes a source table s and uses it to update a target table t. Briefly, a MERGE statement specifies a matching condition to determine which rows of s have at least one matching row in t (under that specified matching condition). It then specifies an open-ended series of conditions to be applied to each row of s paired with actions to be applied on t.
WHEN MATCHED AND c1 THEN x1 specifies that action x1, necessarily an UPDATE or DELETE, is to be applied on t for each matching row in s that satisfies the condition c1. WHEN NOT MATCHED AND c2 THEN x2 specifies that action x2, necessarily an INSERT, is to be applied on t for each non-matching row in s that satisfies the condition c2. The curiously named TRUNCATE statement deletes all the rows from its specified target, bypassing any triggered actions, including compensatory actions, specified for that target. The target must be a base table.
Varrays versus Nested Tables The Nested tables are differing from varrays in the following ways: 1) Varrays have a maximum size, while nested tables do not. 2) Varrays are
Question: a) Given the following relation: Location(loc_id, bldg_code, room, capacity) The underlined field is a primary key. (i) Write a PL/SQL program using the impl
I need SQL Data Base Project Description: Network SQL database and SQL Setup two 4 workstation Skills required are Data Entry, MySQL, SQL
Third Step at defining type SID in SQL CREATE DOMAIN SID AS VARCHAR(5) CHECK ( VALUE IS NOT NULL AND SUBSTRING(VALUE FROM 1 FOR 1) = 'S' AND CAST('+'||SUBSTRING(VALUE
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Example of Shorthand for a row constraint Example: Shorthand for a row constraint ALTER TABLE EXAM_MARK ADD CONSTRAINT Mark_in_range CHECK (Mark BETWEEN 0 AND 100);
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1- You can check attribute names from each table in DBF11 by running for example: desc dbf11.Member; desc dbf11.Agent; desc dbf11.Producer; Because some attribute names in
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