HSQLDB over JDBC：批量执行SQL语句

Question

I need to initialize a database from my Java application. For reasons of code maintainability, I would like to maintain the SQL code separately from the Java code (it is currently in a separate source file).

The first few lines of the file are as follows:

-- 1 - Countries - COUNTRIES.DAT;
drop table Countries if exists;
create table Countries(
  CID integer,
  ECC varchar(2),
  CCD varchar(1),
  NAME varchar(50));

I read the SQL code from the file and store it in a string. Then I do:

PreparedStatement stmt = dbConnection.prepareStatement(sqlString);

This fails with the following exception:

java.sql.SQLSyntaxErrorException: unexpected token: CREATE : line: 2

This looks as if JDBC doesn't like multiple SQL statements in a single PreparedStatement . I have also tried CallableStatement and prepareCall() , with the same result.

Does JDBC provide a way to pass the entire SQL script in one go?

Answer 1

The JDBC standard (and the SQL standard for that matter) assumes a single statement per execute. Some drivers have an option to allow execution of multiple statements in one execute, but technically that option violates the JDBC standard. There is nothing in JDBC itself that supports multi-statement script execution.

You need to separate the statements yourself (on the ; ), and execute them individually, or find a third-party tool that does this for you (eg MyBatis ScriptRunner ).

You might also want to look at something like flyway or liquibase.

Answer 2

To run a hardcoded / loaded from file queries you can use execute like:

Statement stmt = null;
String query = "drop table Countries if exists;
                create table Countries(
                      CID integer,
                      ECC varchar(2),
                      CCD varchar(1),
                      NAME varchar(50));";
try {
    stmt = con.createStatement();
    stmt.execute(query);
} catch (SQLException e ) {
    JDBCTutorialUtilities.printSQLException(e);
} finally {
    if (stmt != null) { stmt.close(); }
}

If you want to run dynamic queries for example to append values you have to use PreparedStatement. For running a query from a file it's not recommended to put dynamic queries in it.