在Teradata中查询运行结果

Question

我在Teradata编辑器中运行以下查询：

SELECT 'EMP_INFO_MAIN' as TABLE_NAME, COUNT(1) as RECORD_COUNT FROM SCHEMA.TABLE1 UNION ALL
SELECT 'EMP_SAL' as TABLE_NAME, COUNT(1) as RECORD_COUNT FROM SCHEMA.TABLE2 UNION ALL
SELECT 'DEPARTMENT_INFO' as TABLE_NAME, COUNT(1) as RECORD_COUNT FROM SCHEMA.TABLE3;

查询给出了以下结果：

TABLE_NAME  | RECORD_COUNT
------------|------------- 
EMP_INFO    | 10 
EMP_SAL     | 11 
DEPARTME    | 110 

第一列未显示完整的表名。 有人可以帮忙吗？

Answer 1

这是一个常见问题。

在Teradata中，UNION的第一个SELECT确定结果数据类型和列名称，因此要么将SELECT的顺序更改为以最长名称开头，要么在第一个SELECT中添加CAST：

SELECT CAST('EMP_INFO_MAIN' AS VARCHAR(20)) as TABLE_NAME, COUNT(1) as RECORD_COUNT FROM SCHEMA.TABLE1 UNION ALL
SELECT 'EMP_SAL' as TABLE_NAME, COUNT(1) as RECORD_COUNT FROM SCHEMA.TABLE2 UNION ALL
SELECT 'DEPARTMENT_INFO' as TABLE_NAME, COUNT(1) as RECORD_COUNT FROM SCHEMA.TABLE3;