![]() ![]() You can use the start value to specify a search location other than the first character position of string_exp2. Returns the starting position of the first occurrence of string_exp1 within the first character position of string_exp2. The following example uses the DECODE clause in a SELECT statement. ![]() ![]() If DEPTNO is not 10, 20, 30, or 40, the expression returns 'NONE'. If DEPTNO is 10, the expression evaluates to 'ACCOUNTING' if DEPTNO is 20, it evaluates to 'RESEARCH' and so on. The following expression decodes the DEPTNO column in the DEPT table. The maximum number of components in the DECODE expression, including the expression, searches, results, and default is 255. If the expression is null, Oracle Database Lite returns the result of the first search that is also null. In a DECODE expression, Oracle Database Lite considers two nulls to be equivalent. If the first result has the datatype CHAR or if the first result is null, then Oracle Database Lite converts the return value to the datatype VARCHAR2. Oracle Database Lite automatically converts the return value to the same datatype as the first result. Oracle Database Lite automatically converts the expression and each search value to the datatype of the first search value before making comparisons. Consequently, Oracle Database Lite never evaluates a search if a previous search is equal to the expression. Oracle Database Lite evaluates each search value only before comparing it to the expression, rather than evaluating all search values before comparing any of them with the expression. The search, result, and default values can be derived from expressions. If the expression and search contain character data, Oracle Database Lite compares them using non-padded comparison semantics. If no match is found, Oracle Database Lite returns default, or, if default is omitted, returns null. If the expression is equal to a search, Oracle Database Lite returns the corresponding result. To evaluate an expression, Oracle Database Lite compares the expression to each search value one by one. Search for an expression's values and then evaluate them in terms of a specified result. SELECT CAST(CURRENT_TIMESTAMP AS VARCHAR(30)) FROM DUAL ĭECODE ( expr, search, result ) SELECT CAST(1E0 AS NUMERIC(12, 2)) FROM DUAL If is numeric and the result cannot be represented without losing leading significant digits, then the following exception is raised: data-exception, numeric value out of range. If is a character string and specifies a character string, then their character repertoire is the same. If is an interval and is an exact numeric, then the interval contains a single date-time field. If is an exact numeric and is an interval, then the interval contains a single date-time field. Table 3-3 Definitions of Conversion Results and Source Operands Result Definitions You can use the CASE function to search for data based on specific conditions or to update values based on a condition. The CASE function specifies conditions and results for a select or update statement. Specifies the result of the associated condition.Īn optional clause specifying the result of any value not described in a condition clause. Table 3-1 Arguments Used with the CASE Function Argument Most functions have an SQL form and an ODBC form that can differ slightly in functionality. You must provide them with an alias that can be used by the GROUP BY function. Single row SQL functions can appear in select lists (except in SELECT statements that contain a GROUP BY clause) and WHERE clauses.Īggregate functions are the set functions: AVG, MIN, MAX, SUM, and COUNT. A single row function returns a value based on a single row in a query, whereas an aggregate function returns a value based on all the rows in a query. These two types differ in the number of database rows on which they act. There are two general types of SQL functions: single row (or scalar) functions and aggregate functions. SQL functions are used exclusively with SQL commands within SQL statements. If passed a null value, most functions return a null value. If passed an argument whose datatype differs from an expected datatype, most functions perform an implicit datatype conversion on the argument before execution. The SQL function format enables functions to operate with zero, one, or more arguments.įunction( argument1, argument2. SQL functions differ from SQL operators in the format in which they appear with their arguments. SQL functions are similar to SQL operators in that both manipulate data items and both return a result. ![]()
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