oracle convert to number

Oracle's conversion function makes conversion between numeric data types and character types very simple. Depending on the way the data is stored, the numeric data types supported by Oracle include NUMBER (precision, scale), BINARY_FLOAT and BINARY_DOUBLE. When you need to store a large amount of data, you can use the NUMBER (precision, scale) type. In addition, when performing data query operations, character type data also needs to be converted into calculable numeric types. At this time, Oracle's conversion function also needs to be used to convert character type data into numeric type data. The purpose of this article is to introduce you to the function method in Oracle for converting character types to numeric types.

1. TO_NUMBER function

TO_NUMBER is the most basic conversion function in Oracle, which can convert most character type data to the NUMBER data type. The syntax format of this function is as follows:

TO_NUMBER(char, [format], [nls_numeric_characters])

Among them, char is the character type data that needs to be converted; format is an optional parameter, which is specified The converted format; nls_numeric_characters is an optional parameter, which specifies the delimiter of the numeric format.

For example, suppose we have the following string '327.5'. If you need to convert it to a numeric type, you can use the following code:

SELECT TO_NUMBER('327.5') FROM DUAL;

Run result:

TO_NUMBER('327.5')

         327.5

Note: If the input string cannot be converted to a valid numeric type, it will cause the operation Time error. In addition, care must be taken to keep the character format consistent with the number format specified in Oracle. For example, you cannot use commas as decimal separators in numeric strings because in some countries commas serve as thousands separators.

2. ROUND function

ROUND function can round numbers. Its syntax is as follows:

ROUND(number,[decimal_places])

Among them, number represents the number that needs to be rounded, and decimal_places represents the number of decimal places that need to be retained.

For example, assuming we need to keep the number 3.1415926 to two decimal places, we can use the following code:

SELECT ROUND(3.1415926,2) FROM DUAL;

Running results ：

ROUND(3.1415926,2)

          3.14

3. FLOOR function

The FLOOR function can round numbers down. Its syntax format is as follows:

FLOOR(number)

Among them, number represents the number that needs to be rounded down.

For example, assuming we need to round down the number 3.7, we can use the following code:

SELECT FLOOR(3.7) FROM DUAL;

Running results:

FLOOR(3.7)

     3

4. CEIL function

The CEIL function can round numbers up. Its syntax is as follows:

CEIL(number)

Among them, number represents the number that needs to be rounded up.

For example, assuming we need to round up the number 3.3, we can use the following code:

SELECT CEIL(3.3) FROM DUAL;

Running results:

CEIL(3.3)

    4

5. TRUNC function

TRUNC function can intercept numbers. Its syntax format is as follows:

TRUNC (number,[decimal_places])

Among them, number represents the number that needs to be intercepted, and decimal_places represents the number of decimal places that need to be retained.

For example, assuming we need to keep the number 3.1415926 to two decimal places, we can use the following code:

SELECT TRUNC(3.1415926,2) FROM DUAL;

Running results ：

TRUNC(3.1415926,2)

          3.14

Summary

This article introduces five commonly used function methods in Oracle to convert character types to numeric types. In addition to describing the syntactic format of these functions, some examples of using these functions are also provided. It should be noted that these functions need to comply with the number format specified in Oracle when converting between character types and numeric types.

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