mysql NOW' is not a recognized built-in function name.

原创

mob649e816aeef7 2023-08-25 19:34:10 ©著作权

©著作权归作者所有：来自51CTO博客作者mob649e816aeef7的原创作品，请联系作者获取转载授权，否则将追究法律责任

MySQL - NOW() is not a recognized built-in function name

MySQL is a popular open-source relational database management system used by many applications and websites. It provides a rich set of functions and features for managing and manipulating data. One of the commonly used functions is NOW(), which is used to retrieve the current date and time.

However, sometimes you may encounter an error message like "NOW' is not a recognized built-in function name." This can be confusing, especially if you know that NOW() is a built-in function in MySQL. In this article, we will explore why this error occurs and how to solve it.

Understanding the Error

The error message "NOW' is not a recognized built-in function name" typically occurs when you try to execute a query that includes the NOW() function, but MySQL doesn't recognize it as a valid function. This can happen due to various reasons:

Incorrect Syntax: The most common reason for this error is a syntax error in the query. Make sure that the NOW() function is spelled correctly and enclosed within parentheses.
```
SELECT NOW(); -- Correct usage of NOW() function
SELECT NOW; -- Incorrect usage, missing parentheses
SELECT 'NOW()'; -- Incorrect usage, NOW() is treated as a string
```
Function Not Supported: Some versions of MySQL may not support the NOW() function. This can happen if you are using an outdated version or a fork of MySQL that doesn't include this function. In such cases, you can try using alternative functions like SYSDATE() or CURRENT_TIMESTAMP.
Function Aliasing: If you have created a function or procedure named NOW, it can cause conflicts with the built-in NOW() function. MySQL will prioritize the user-defined function over the built-in function, resulting in the error. To resolve this, you can either rename your function or use the fully qualified function name, MYSQL.NOW().
```
CREATE FUNCTION NOW() -- User-defined function named NOW
RETURNS DATETIME
BEGIN
  RETURN CURRENT_TIMESTAMP;
END;

SELECT NOW(); -- Error: NOW is ambiguous, use MYSQL.NOW()

SELECT MYSQL.NOW(); -- Fully qualified function name
```
Database Compatibility Mode: Some databases, such as Microsoft SQL Server, have a compatibility mode to mimic the behavior of other database systems. If you are migrating from a different database system and using the compatibility mode, the NOW() function may not be recognized. You can check the compatibility mode settings and adjust accordingly.

Resolving the Error

To resolve the "NOW' is not a recognized built-in function name" error, you can follow these steps:

Check Syntax: Double-check the syntax of your query to ensure that the NOW() function is correctly written and enclosed within parentheses.
Use Alternative Functions: If your MySQL version doesn't support the NOW() function or you are unsure, try using alternative functions like SYSDATE() or CURRENT_TIMESTAMP.
```
SELECT SYSDATE();
SELECT CURRENT_TIMESTAMP;
```
Avoid Function Aliasing: If you have a user-defined function or procedure named NOW, consider renaming it to avoid conflicts with the built-in function. Alternatively, use the fully qualified function name, MYSQL.NOW().
Check Compatibility Mode: If you are using a database compatibility mode, make sure that it doesn't interfere with the recognition of the NOW() function. Adjust the compatibility mode settings if necessary.

Conclusion

The "NOW' is not a recognized built-in function name" error in MySQL can be caused by various factors, such as incorrect syntax, unsupported function, function aliasing, or compatibility mode settings. By understanding the possible causes and following the steps mentioned above, you can effectively resolve this error and make use of the NOW() function or its alternatives.

Remember to always double-check the syntax of your queries and keep your MySQL server up to date to ensure optimal functionality. Happy coding!