@Table Annotation in JPA

Direct Answer

@Table customizes the primary table used by an entity, including its name, schema, catalog, unique constraints, and indexes in schema-generation metadata. Use it when defaults do not match the database. The default schema is whatever the connection/provider/database resolves; it is not universally a schema named public.

Code Example

import jakarta.persistence.*;

@Entity
@Table(
    name = "users",                 // class User → table users
    schema = "sales",               // lives in the sales schema
    uniqueConstraints = @UniqueConstraint(
        name = "uq_email_per_tenant",
        columnNames = {"email", "tenant_id"} // unique TOGETHER
    )
)
public class User {
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String email;
    @Column(name = "tenant_id")
    private Long tenantId;
}

Common Mistakes & Pitfalls

• Skipping @Table with plural names — class User won't find table users; set name.
• Forgetting schema — tables in sales.orders aren't auto-discovered; specify the schema.
• @Column(unique=true) for composite uniqueness — makes each column unique individually; use @Table(uniqueConstraints=...).
• Relying on naming strategy blindly — Spring's implicit naming may or may not match your existing schema.