Let's talk about some commonly used Oracle query functions

Oracle database is a relational database management system. It supports SQL and PL/SQL languages ​​and provides numerous query functions to facilitate users' data query and analysis. In this article, we will introduce some commonly used Oracle query functions, hoping to be helpful to your data query and analysis.

1. COUNT function

The COUNT function is used to count the number of rows in the specified column. Its syntax is as follows:

SELECT COUNT(column_name) FROM table_name;

Among them, column_name is the name of the column that needs statistics, and table_name is the name of the table that needs to be queried. If you want to count all rows, you can use the wildcard *. The specific syntax is as follows:

SELECT COUNT(*) FROM table_name;

2. SUM function

The SUM function is used to calculate the values ​​in the specified column. and. Its syntax is as follows:

SELECT SUM(column_name) FROM table_name;

Among them, column_name is the name of the column that needs to be summed, and table_name is the name of the table that needs to be queried.

3. AVG function

The AVG function is used to return the average of the values ​​in a specified column. Its syntax is as follows:

SELECT AVG(column_name) FROM table_name;

Among them, column_name is the name of the column that needs to be averaged, and table_name is the name of the table that needs to be queried.

4. MAX function

The MAX function returns the maximum value in a specified column. Its syntax is as follows:

SELECT MAX(column_name) FROM table_name;

Among them, column_name is the name of the column that needs to be queried for the maximum value, and table_name is the name of the table that needs to be queried.

5. MIN function

The MIN function returns the minimum value in a specified column. Its syntax is as follows:

SELECT MIN(column_name) FROM table_name;

Among them, column_name is the name of the column that needs to be queried for the minimum value, and table_name is the name of the table that needs to be queried.

6. CONCAT function

The CONCAT function is used to concatenate two or more strings. Its syntax is as follows:

SELECT CONCAT(string1, string2, string3) FROM table_name;

Among them, string1, string2, and string3 are the strings that need to be connected, and there can be multiple. table_name is the name of the table to be queried.

7. SUBSTR function

The SUBSTR function is used to return the substring in the specified string. Its syntax is as follows:

SELECT SUBSTR(string, start_position, length) FROM table_name;

Among them, string is the string that needs to be queried for the substring, start_position specifies the starting position of the substring (starting from 1), and length specifies the length of the substring. table_name is the name of the table to be queried.

8. TRUNC function

The TRUNC function is used to intercept the integer part or decimal part of the specified value. Its syntax is as follows:

SELECT TRUNC(number, decimals) FROM table_name;

Among them, number is the value that needs to be intercepted, and decimals specifies the number of decimal places that need to be retained. If decimals is omitted, the integer part is retained by default. table_name is the name of the table to be queried.

The above are some commonly used Oracle query functions, which are suitable for almost all application fields. Of course, Oracle database also provides many other functions. For a complete list of functions, please refer to Oracle official documentation. I hope this article will be helpful to your data query and analysis work.

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