What is the usage of oracle to number?

oracle to number is a function used to convert strings to numbers. It accepts format strings and can specify character sets and collations. Common usage: 1. Convert strings to integers; 2. Convert strings with decimals to floating point numbers; 3. Use formatted strings for conversion; 4. Specify character sets and collation rules.

#The operating environment of this article: Windows 10 system, Oracle version 19c, dell g3 computer.

Oracle's TO_NUMBER function is a function that converts character data types to numeric data types. It accepts a string argument and attempts to convert it to a number. If the conversion fails, an error is raised.

The syntax of the TO_NUMBER function is as follows:

TO_NUMBER(char [, format_mask [, nls_language ]])

char is the string to be converted to a number.

format_mask is an optional parameter used to specify the format of the input string. It can be a fixed format pattern or a template.

nls_language is an optional parameter used to specify the character set and collation.

Here are some examples of using the TO_NUMBER function:

1. Convert the string to an integer:

SELECT TO_NUMBER('123') FROM dual;

This will return the number 123.

2. Convert a string with decimals to a floating point number:

SELECT TO_NUMBER('3.14') FROM dual;

This will return the number 3.14.

3. Use the format string to convert:

SELECT TO_NUMBER('1,234.567', '999G999D999') FROM dual;

This will return 1234.567. In the format string, G represents the thousands separator and D represents the decimal point.

4. Specify the character set and collation:

SELECT TO_NUMBER('1.234', '999999D9999', 'NLS_NUMERIC_CHARACTERS = ''. ''') FROM dual;

This will return the number 1.234. In this example, we specify that the character for the decimal point is a period.

It should be noted that the TO_NUMBER function can only convert legal numeric strings. If the string passed to the function contains non-numeric characters or is not in the required format, an error is thrown. In this case, other functions such as the REGEXP_REPLACE function can be used to clear non-numeric characters.

In addition, the TO_NUMBER function can also be used with other numeric functions and operators, such as basic arithmetic operations, aggregate functions, and conditional expressions.

Summary

TO_NUMBER function is a function in Oracle used to convert a string to a number. It accepts format strings and can specify character sets and collations. However, care needs to be taken with the format and content of the input string to avoid errors.

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