Java Spring Boot nad PostgreSQL中文件data.SQL中的错误SQL语句语法

我想创建一个将由PostgreSQL数据库创建的条件查询

IF ( NO EXISTS(SELECT * FROM users WHERE username = 'JonkiPro'))
BEGIN
  INSERT INTO UserEntity(id, username, email, password, enabled, registration_date, modified_date)
  VALUES(1, 'JonkiPro', 'someemail@someemail.com,', 'safsd', true, GetDate(), GetDate())
END

但是，编译过程中会发生错误

    Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSourceInitializer': Invocation of init method failed; nested exception is org.springframework.jdbc.datasource.init.ScriptStatementFailedException: Failed to execute SQL script statement #1 of class path resource [db/init/data.sql]: IF ( NO EXISTS(SELECT * FROM users WHERE username = 'JonkiPro')); nested exception is org.postgresql.util.PSQLException: BŁĄD: błąd składni w lub blisko "IF"
      Pozycja: 1
        at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:137) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
 ...

    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1633) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
            at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
            ... 99 common frames omitted
        Caused by: org.springframework.jdbc.datasource.init.ScriptStatementFailedException: Failed to execute SQL script statement #1 of class path resource [db/init/data.sql]: IF ( NO EXISTS(SELECT * FROM users WHERE username = 'JonkiPro')); nested exception is org.postgresql.util.PSQLException: BŁĄD: błąd składni w lub blisko "IF"
          Pozycja: 1
            at ...
            ... 114 common frames omitted
        Caused by: org.postgresql.util.PSQLException: ERROR: syntax error in or near "IF".
          Pozycja: 1
            at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2455) ~[postgresql-9.4.1212.jre7.jar:9.4.1212.jre7]
            at ...

我不知道他为什么不理解订单

IF

。但是，当我在

DO$$之间执行命令时$$它拒绝异常

      Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSourceInitializer': Invocation of init method failed; nested exception is org.springframework.jdbc.datasource.init.UncategorizedScriptException: Failed to execute database script from resource [class path resource [db/init/data.sql]]; nested exception is java.lang.ArrayIndexOutOfBoundsException
     ...
            ... 99 common frames omitted
        Caused by: org.springframework.jdbc.datasource.init.UncategorizedScriptException: Failed to execute database script from resource [class path resource [db/init/data.sql]]; nested exception is java.lang.ArrayIndexOutOfBoundsException
...

    org.springframework.jdbc.datasource.init.ScriptUtils.executeSqlScript(ScriptUtils.java:470) ~[spring-jdbc-4.3.10.RELEASE.jar:4.3.10.RELEASE]
                ... 127 common frames omitted

我的第二个问题是如何添加一个命令，将数据输入到块
BEGIN。。。END
有关有条件地创建用户的另一种方法，请参阅，因为如果不先加载PL/pgSQL扩展名，就无法使用IF语句。在您的情况下，这将导致如下查询：

INSERT INTO UserEntity(id, username, email, password, enabled, registration_date, modified_date)
SELECT
    1, 'JonkiPro', 'someemail@someemail.com,', 'safsd', true, GetDate(), GetDate()
WHERE NOT EXISTS (
    SELECT * FROM users WHERE username = 'JonkiPro'
);

我有一个错误：关系“userentity”不存在。在“UserEntity”处是否应该是表的名称？