Q: How to perform DDL with schema?

A: To generate and execute DDL from a schema, use the schema method of TableQuery.

The schema method is a convenient mechanism that automatically generates DDL statements such as CREATE, DROP, TRUNCATE, etc. from table definitions.
The following sample code demonstrates how to generate DDL for UserTable and execute table creation, data deletion, and table deletion in sequence.

// ...existing code...
// Example: DDL operations for UserTable

// Assuming UserTable is defined
val userSchema = TableQuery[UserTable].schema

// Examples of generating DDL statements
val createDDL   = userSchema.createIfNotExists.statements
val dropDDL     = userSchema.dropIfExists.statements
val truncateDDL = userSchema.truncate.statements

// If you want to check the generated DDL statements
createDDL.foreach(println)    // CREATE TABLE statement will be output
dropDDL.foreach(println)      // DROP TABLE statement will be output
truncateDDL.foreach(println)  // TRUNCATE TABLE statement will be output

// Example of executing DDL operations
provider
  .use { conn =>
    DBIO.sequence(
        userSchema.createIfNotExists,
        userSchema.truncate,
        userSchema.dropIfExists
      )
      .commit(conn)
  }
// ...existing code...

The code above implements operations that create tables while checking for their existence, reset table data as needed, and then delete the tables themselves.

References

• Schema Definition Details
  
• Database Operations