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I have an pl\sql script where I want to set the table name used in the script to a variable. So, from some examples I found on the web, I wrote the code below. The first section works, so I think...
The UNION operator is a set operator that combines result sets of two or more SELECT statements into a single result set. The following illustrates the syntax of the UNION operator that combines the result sets of two queries: SELECT column_list_1 FROM T1 UNION SELECT column_list_1 FROM T2; Code language: SQL (Structured Query Language) (sql)
25 Σεπ 2018 · The Union operator combines the results of two or more queries into a single result set that includes all the rows that belong to all queries in the Union. In simple terms, it combines the two or more row sets and keeps duplicates. For example, the table ‘A’ has 1,2, and 3 and the table ‘B’ has 3,4,5.
The following statement combines the results of two queries with the UNION operator, which eliminates duplicate selected rows. This statement shows that you must match data type (using the TO_CHAR function) when columns do not exist in one or the other table:
UNION ALL Syntax. The UNION operator selects only distinct values by default. To allow duplicate values, use UNION ALL: SELECT column_name (s) FROM table1. UNION ALL. SELECT column_name (s) FROM table2; Note: The column names in the result-set are usually equal to the column names in the first SELECT statement.
The syntax for the UNION operator in SQL is: SELECT expression1, expression2, ... expression_n. FROM tables. [WHERE conditions] UNION. SELECT expression1, expression2, ... expression_n. FROM tables. [WHERE conditions]; Parameters or Arguments. expression1, expression2, expression_n. The columns or calculations that you wish to retrieve. tables.
The syntax for the UNION operator in Oracle/PLSQL is: SELECT expression1, expression2, ... expression_n FROM tables [WHERE conditions] UNION SELECT expression1, expression2, ... expression_n FROM tables [WHERE conditions];
