Sql updating multiple rows based on a select statement

The syntax for row values and the circumstances in which row values can be used are illustrated in examples below.

Two row values are compared by looking at the constituent scalar values from left to right. The overall result of comparison is NULL if it is possible to make the result either true or false by substituting alternative values in place of the constituent NULLs.

Any of the row values in the previous example could be replace by a subquery that returns three columns and the same answer would result.

For example: For a row-value IN operator, the left-hand side (hereafter "LHS") can be either a parenthesized list of values or a subquery with multiple columns.

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But the second form is made easier for humans to read by grouping the query parameters together into a single row value rather than scattering them across the WHERE clause.Consider the following two UPDATE statements: Both UPDATE statements do exactly the same thing.(They generate identical bytecode.) But the first form, the row value form, seems to make it clearer that the intent of the statement is to swap the values in columns A and B.In this article, we are going to look at four scenarios for Oracle cross table update. Category_ID) where exists ( select * from Categories b where b. These columns uniquely identify a record in a table.Suppose we have two tables Categories and Categories_Test. The common column in the two tables is CATEGORY_ID. Please note that query below is used for illustration purpose because Category_ID alone is primary key.

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