Solving “Syntax error in SQL statement: expected “identifier”

When working with JPA (Java Persistence API) and defining entity classes, it’s crucial to avoid using reserved words as identifiers for attributes or table names. Failure to do so may lead to SQL syntax errors, as demonstrated by the given issue.

In this tutorial, we’ll walk through the steps to resolve the SQL syntax error caused by using reserved words in a JPA entity class.

Step 1: Understanding the Issue

The error message indicates a syntax error in the SQL statement generated by Hibernate, the JPA provider being used. Specifically, it complains about the usage of a reserved word in the SQL statement. In the provided example, the word “value” is causing the issue:

Caused by: org.h2.jdbc.JdbcSQLSyntaxErrorException: Syntax error in SQL statement "create table Person (id bigint not null, name varchar(255) not null, surname varchar(255) not null, [*]value varchar(255) not null, primary key (id))"; expected "identifier"; SQL statement:
create table Person (id bigint not null, name varchar(255) not null, surname varchar(255) not null, value varchar(255) not null, primary key (id)) [42001-224]
Solving "Syntax error in SQL statement: expected "identifier"

Step 2: Identifying Reserved Words

Reserved words are keywords in a programming language or database system that have special meanings and cannot be used as identifiers such as table names, column names, or attribute names. Some examples of reserved words in SQL and JPA include:

  • SQL Reserved Words: These are reserved words in the SQL language, and their usage in table or column names can lead to syntax errors. Examples include “value”, “select”, “insert”, “update”, “delete”, etc.
  • JPA/Hibernate Reserved Words: In addition to SQL reserved words, JPA/Hibernate have their own set of reserved words that you should avoid. For example, “table”, “column”, “id”, “generatedvalue”, etc.

Here is, for example, how to reproduce the issue by using the value keyword:

@Entity
public class Model {

    @Id
    @GeneratedValue
    private Long id;

    @NotNull
    private String value;	

}

Step 3: Resolving the Issue

To resolve the SQL syntax error caused by using reserved words in the JPA entity class, follow these steps:

  1. Identify Reserved Words: Go through your entity class and identify any attributes or table names that are using reserved words.
  2. Rename Attributes: Rename the attributes in your entity class to avoid using reserved words. In the provided example, the attribute “value” should be renamed to something else, such as “data”, “content”, or any other appropriate name that is not a reserved word.
  3. Update Entity Class: Modify your entity class to reflect the changes made in step 2. Replace the reserved word with the new name chosen for the attribute.
  4. Recompile and Test: After making the necessary changes, recompile your code and test it again to ensure that the SQL syntax error is resolved.

Conclusion

In conclusion, when working with JPA entities, always be mindful of reserved words in both SQL and JPA/Hibernate. Avoid using them as identifiers for attributes, table names, or column names to prevent SQL syntax errors. If you encounter such errors, identify the reserved words causing the issue and rename them accordingly in your entity classes.