How to convert Oracle characters to numbers

Oracle is a popular relational database management system that is often used to process data. In the process of using Oracle, characters and numbers are essential types. Sometimes it is necessary to convert characters into numbers for calculation and analysis, which requires the use of some functions provided by Oracle.

1. TO_NUMBER function

In Oracle, the TO_NUMBER function can convert character types to numeric types. The syntax is as follows:

TO_NUMBER(String, [Format], [Language Settings])

Among them, the string is the character type data that needs to be converted, and the format is optional. Specifies the parsing format of the string. The language setting is also optional and is used to specify internationalization settings.

For example, we have a string '123.456', which needs to be converted into numeric data for calculation. This can be achieved using the following statement:

SELECT TO_NUMBER('123.456') FROM dual

The running result is: 123.456.

2. CAST function

In Oracle, the CHARTO_NUMBER function can convert character data into numeric data. However, if you want to explicitly convert the data to a numeric type in the query, you can use the CAST function.

The syntax of the CAST function is as follows:

CAST (Character data that needs to be converted to a number AS NUMBER)

For example, we have a string '789.012', which needs to be converted It is converted into numerical data for calculation. This can be achieved using the following statement:

SELECT CAST('789.012' AS NUMBER) FROM dual

The running result is: 789.012.

3. Use DECODE function for conversion

The DECODE function is one of the conversion functions in Oracle database, which can convert one value to another value based on conditions. When using it, you need to specify the value to be converted, its corresponding conversion value and the default conversion value.

The syntax of the DECODE function is as follows:

DECODE (the value to be converted, when the value is equal to the target value 1, the value 1 is returned, when the value is equal to the target value 2, the value 2 is returned , ..., default return value)

For example, we need to convert a string '100' to an integer type. This can be achieved using the following statement:

SELECT DECODE('100', NULL, 0, '100', 1, -1) FROM dual

The running result is: 1.

Summary:

In Oracle, character data can be converted into numeric data using the TO_NUMBER, CAST and DECODE functions. Among them, the TO_NUMBER function is suitable for converting string type data into numbers, the CAST function can explicitly convert character data into numeric data, and the DECODE function can convert one value into another value based on conditions. When using it, you need to select and use it according to the specific situation.

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