Is oracle not case sensitive?

Oracle is a widely used database management system that supports many different programming languages ​​and operating systems. In Oracle, a common problem is case, because Oracle is not case sensitive, which means it treats uppercase and lowercase letters as the same characters. Therefore, when writing Oracle queries, you must be careful about casing issues.

First, we need to understand the basics of Oracle query language. Oracle Query Language is a Structured Query Language (SQL) that allows us to retrieve and process data from a database. In Oracle, we use SELECT statement to retrieve data. The syntax of a basic SELECT statement is as follows:

SELECT column1, column2, ... FROM table_name WHERE condition;

In this SELECT statement, we specify the column (column) to be retrieved, and use the FROM clause to specify the table (table) to be retrieved. We can also specify a condition using the WHERE clause, which will only return data that matches the condition.

When writing a SELECT statement, please note that Oracle is not case-sensitive. This means we can write column names, table names, and keywords in any case. For example, the following two statements are equivalent and will return the same result:

SELECT employee_name FROM employee_table;

SELECT EMPLOYEE_NAME FROM EMPLOYEE_TABLE;

However, in practice, it is recommended to use consistent casing rules so that the code is easier to read and maintain. If we don't handle capitalization well, it can lead to confusion and errors in our code.

Another important issue is using functions in Oracle. Functions are pieces of code that accept parameters and return values. For example, in Oracle, we can use the UPPER function to convert a string to uppercase and the LOWER function to convert a string to lowercase. The following are examples of UPPER and LOWER functions:

SELECT UPPER(employee_name) FROM employee_table;

SELECT LOWER(employee_name) FROM employee_table;

Similarly, we need to pay attention to Oracle's flexibility in the case of function names. Although UPPER and LOWER are standard Oracle function names, in practice, there may be several different case combinations. For example, the following two statements are equivalent:

SELECT Upper(employee_name) FROM Employee_Table;

SELECT uPpEr(Employee_Name) FROM eMpLoYeE_tAbLe;

When writing complex queries, you may use multiple tables and multiple columns. In this case, the casing issue may become more complicated. Therefore, we should maintain good habits and avoid using mixed case in table and column names. A common convention is to use underscores to separate words, such as employee_name or employee_table.

Finally, we need to pay attention to Oracle's case-sensitive parameters. Although Oracle queries themselves are not case-sensitive, some parameters are case-sensitive. For example, in Oracle, we can use the DESCRIBE command to view the structure of a table, but this command is case-sensitive to the table name. Therefore, the following two statements will return different results:

DESCRIBE employee_table;

DESCRIBE EMPLOYEE_TABLE;

In short, although Oracle is not case-sensitive, it does not mean that we can ignore case issues. When writing Oracle queries, we need to maintain consistent capitalization habits to avoid confusion and errors. At the same time, you also need to pay attention to case-sensitive parameter and function names. By following these best practices, we can write Oracle queries that are clearer and easier to read and maintain.

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