hi、
我现在使用flink sql完成如下sql语句，但是程序无法运行，请问这个功能要怎么实现：
select null as person_uuid from tablename
抛出异常：
org.apache.flink.client.program.ProgramInvocationException: The main method
caused an error: SQL validation failed. From line 1, column 47 to line 1,
column 50: Illegal use of 'NULL'
at
org.apache.flink.client.program.PackagedProgram.callMainMethod(PackagedProgram.java:302)
at
org.apache.flink.client.program.PackagedProgram.invokeInteractiveModeForExecution(PackagedProgram.java:198)
at org.apache.flink.client.ClientUtils.executeProgram(ClientUtils.java:149)
at
org.apache.flink.client.cli.CliFrontend.executeProgram(CliFrontend.java:699)
at org.apache.flink.client.cli.CliFrontend.run(CliFrontend.java:232)
at
org.apache.flink.client.cli.CliFrontend.parseParameters(CliFrontend.java:916)
at
org.apache.flink.client.cli.CliFrontend.lambda$main$10(CliFrontend.java:992)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at
org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1917)
at
org.apache.flink.runtime.security.contexts.HadoopSecurityContext.runSecured(HadoopSecurityContext.java:41)
at org.apache.flink.client.cli.CliFrontend.main(CliFrontend.java:992)
Caused by: org.apache.flink.table.api.ValidationException: SQL validation
failed. From line 1, column 47 to line 1, column 50: Illegal use of 'NULL'
at org.apache.flink.table.planner.calcite.FlinkPlannerImpl.org
$apache$flink$table$planner$calcite$FlinkPlannerImpl$$validate(FlinkPlannerImpl.scala:146)
at
org.apache.flink.table.planner.calcite.FlinkPlannerImpl.validate(FlinkPlannerImpl.scala:108)
at
org.apache.flink.table.planner.operations.SqlToOperationConverter.convert(SqlToOperationConverter.java:187)
at
org.apache.flink.table.planner.delegation.ParserImpl.parse(ParserImpl.java:78)
at
org.apache.flink.table.api.internal.TableEnvironmentImpl.sqlQuery(TableEnvironmentImpl.java:664)
at com.akulaku.blade.main.StreamingMain.main(StreamingMain.java:103)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at
org.apache.flink.client.program.PackagedProgram.callMainMethod(PackagedProgram.java:288)
... 11 more
Caused by: org.apache.calcite.runtime.CalciteContextException: From line 1,
column 47 to line 1, column 50: Illegal use of 'NULL'
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at
org.apache.calcite.runtime.Resources$ExInstWithCause.ex(Resources.java:457)
at org.apache.calcite.sql.SqlUtil.newContextException(SqlUtil.java:839)
at org.apache.calcite.sql.SqlUtil.newContextException(SqlUtil.java:824)
at
org.apache.calcite.sql.validate.SqlValidatorImpl.newValidationError(SqlValidatorImpl.java:5089)
at
org.apache.calcite.sql.validate.SqlValidatorImpl.inferUnknownTypes(SqlValidatorImpl.java:1906)
at
org.apache.calcite.sql.validate.SqlValidatorImpl.inferUnknownTypes(SqlValidatorImpl.java:1968)
at
org.apache.calcite.sql.validate.SqlValidatorImpl.expandSelectItem(SqlValidatorImpl.java:479)
at
org.apache.calcite.sql.validate.SqlValidatorImpl.validateSelectList(SqlValidatorImpl.java:4255)
at
org.apache.calcite.sql.validate.SqlValidatorImpl.validateSelect(SqlValidatorImpl.java:3523)
at
org.apache.calcite.sql.validate.SelectNamespace.validateImpl(SelectNamespace.java:60)
at
org.apache.calcite.sql.validate.AbstractNamespace.validate(AbstractNamespace.java:84)
at
org.apache.calcite.sql.validate.SqlValidatorImpl.validateNamespace(SqlValidatorImpl.java:1110)
at
org.apache.calcite.sql.validate.SqlValidatorImpl.validateQuery(SqlValidatorImpl.java:1084)
at org.apache.calcite.sql.SqlSelect.validate(SqlSelect.java:232)
at
org.apache.calcite.sql.validate.SqlValidatorImpl.validateScopedExpression(SqlValidatorImpl.java:1059)
at
org.apache.calcite.sql.validate.SqlValidatorImpl.validate(SqlValidatorImpl.java:766)
at org.apache.flink.table.planner.calcite.FlinkPlannerImpl.org
$apache$flink$table$planner$calcite$FlinkPlannerImpl$$validate(FlinkPlannerImpl.scala:141)
... 21 more
Caused by: org.apache.calcite.sql.validate.SqlValidatorException: Illegal
use of 'NULL'
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at
org.apache.calcite.runtime.Resources$ExInstWithCause.ex(Resources.java:457)
at org.apache.calcite.runtime.Resources$ExInst.ex(Resources.java:550)
