sql - 使用 Teradata 系统表获取列类型

Question

我想从 dbc.columns 之类的 teradata 系统表中获取实际的列类型。

该表具有列 columntype 但它没有给出实际的数据类型。

我可以得到输出

select type(columnname) from table
output: varchar2(20) 

但是有 1000 个表和 50000 列。请提出一些可以从元数据本身为我提供列的实际列类型的查询

Answer 1

对于 View ，列类型将为 NULL，因为它是在运行时解析的。

对于单个表，您可以执行 HELP COLUMN viewname.*; 以获取实际数据类型。

顺便说一句，Teradata 中没有像 Varchar2 这样的类型，那就是 Oracle :-)

编辑:
似乎您想要列的完整定义。这是一个 SQL UDF，返回与您在 SHOW TABLE 中找到的相同信息(我不确定是否涵盖了 TD14.10，我还没有检查):

REPLACE FUNCTION DataTypeString 
 (
  ColumnType CHAR(2),
  ColumnLength INT,
  DecimalTotalDigits SMALLINT,
  DecimalFractionalDigits SMALLINT,
  CharType SMALLINT,
  ColumnUDTName VARCHAR(128) CHARACTER SET UNICODE
 )
RETURNS VARCHAR(60)
LANGUAGE SQL
CONTAINS SQL
DETERMINISTIC
SQL SECURITY DEFINER
COLLATION INVOKER
INLINE TYPE 1
RETURN 
  CASE ColumnType
    WHEN 'BF' THEN 'BYTE('            || TRIM(CAST(ColumnLength AS INTEGER)) || ')'
    WHEN 'BV' THEN 'VARBYTE('         || TRIM(CAST(ColumnLength AS INTEGER)) || ')'
    WHEN 'CF' THEN 'CHAR('            || TRIM(CAST(ColumnLength AS INTEGER)) || ')'
    WHEN 'CV' THEN 'VARCHAR('         || TRIM(CAST(ColumnLength AS INTEGER)) || ')'
    WHEN 'D ' THEN 'DECIMAL('         || TRIM(DecimalTotalDigits) || ','
                                      || TRIM(DecimalFractionalDigits) || ')'
    WHEN 'DA' THEN 'DATE'
    WHEN 'F ' THEN 'FLOAT'
    WHEN 'I1' THEN 'BYTEINT'
    WHEN 'I2' THEN 'SMALLINT'
    WHEN 'I8' THEN 'BIGINT'
    WHEN 'I ' THEN 'INTEGER'
    WHEN 'AT' THEN 'TIME('            || TRIM(DecimalFractionalDigits) || ')'
    WHEN 'TS' THEN 'TIMESTAMP('       || TRIM(DecimalFractionalDigits) || ')'
    WHEN 'TZ' THEN 'TIME('            || TRIM(DecimalFractionalDigits) || ')' || ' WITH TIME ZONE'
    WHEN 'SZ' THEN 'TIMESTAMP('       || TRIM(DecimalFractionalDigits) || ')' || ' WITH TIME ZONE'
    WHEN 'YR' THEN 'INTERVAL YEAR('   || TRIM(DecimalTotalDigits) || ')'
    WHEN 'YM' THEN 'INTERVAL YEAR('   || TRIM(DecimalTotalDigits) || ')'      || ' TO MONTH'
    WHEN 'MO' THEN 'INTERVAL MONTH('  || TRIM(DecimalTotalDigits) || ')'
    WHEN 'DY' THEN 'INTERVAL DAY('    || TRIM(DecimalTotalDigits) || ')'
    WHEN 'DH' THEN 'INTERVAL DAY('    || TRIM(DecimalTotalDigits) || ')'      || ' TO HOUR'
    WHEN 'DM' THEN 'INTERVAL DAY('    || TRIM(DecimalTotalDigits) || ')'      || ' TO MINUTE'
    WHEN 'DS' THEN 'INTERVAL DAY('    || TRIM(DecimalTotalDigits) || ')'      || ' TO SECOND('
                                      || TRIM(DecimalFractionalDigits) || ')'
    WHEN 'HR' THEN 'INTERVAL HOUR('   || TRIM(DecimalTotalDigits) || ')'
    WHEN 'HM' THEN 'INTERVAL HOUR('   || TRIM(DecimalTotalDigits) || ')'      || ' TO MINUTE'
    WHEN 'HS' THEN 'INTERVAL HOUR('   || TRIM(DecimalTotalDigits) || ')'      || ' TO SECOND('
                                      || TRIM(DecimalFractionalDigits) || ')'
    WHEN 'MI' THEN 'INTERVAL MINUTE(' || TRIM(DecimalTotalDigits) || ')'
    WHEN 'MS' THEN 'INTERVAL MINUTE(' || TRIM(DecimalTotalDigits) || ')'      || ' TO SECOND('
                                      || TRIM(DecimalFractionalDigits) || ')'
    WHEN 'SC' THEN 'INTERVAL SECOND(' || TRIM(DecimalTotalDigits) || ',' 
                                      || TRIM(DecimalFractionalDigits) || ')'
    WHEN 'BO' THEN 'BLOB('            || TRIM(CAST(ColumnLength AS INTEGER)) || ')'
    WHEN 'CO' THEN 'CLOB('            || TRIM(CAST(ColumnLength AS INTEGER)) || ')'

    WHEN 'PD' THEN 'PERIOD(DATE)'     
    WHEN 'PM' THEN 'PERIOD(TIMESTAMP('|| TRIM(DecimalFractionalDigits) || ')' || ' WITH TIME ZONE'
    WHEN 'PS' THEN 'PERIOD(TIMESTAMP('|| TRIM(DecimalFractionalDigits) || '))'
    WHEN 'PT' THEN 'PERIOD(TIME('     || TRIM(DecimalFractionalDigits) || '))'
    WHEN 'PZ' THEN 'PERIOD(TIME('     || TRIM(DecimalFractionalDigits) || '))' || ' WITH TIME ZONE'
    WHEN 'UT' THEN COALESCE(ColumnUDTName,  '<Unknown> ' || ColumnType)

    WHEN '++' THEN 'TD_ANYTYPE'
    WHEN 'N'  THEN 'NUMBER('          || CASE WHEN DecimalTotalDigits = -128 THEN '*' ELSE TRIM(DecimalTotalDigits) END
                                      || CASE WHEN DecimalFractionalDigits IN (0, -128) THEN '' ELSE ',' || TRIM(DecimalFractionalDigits) END
                                      || ')'
    WHEN 'A1' THEN COALESCE('SYSUDTLIB.' || ColumnUDTName,  '<Unknown> ' || ColumnType)
    WHEN 'AN' THEN COALESCE('SYSUDTLIB.' || ColumnUDTName,  '<Unknown> ' || ColumnType)

    ELSE '<Unknown> ' || ColumnType
  END 
  || CASE
        WHEN ColumnType IN ('CV', 'CF', 'CO') 
        THEN CASE CharType 
                WHEN 1 THEN ' CHARACTER SET LATIN'
                WHEN 2 THEN ' CHARACTER SET UNICODE'
                WHEN 3 THEN ' CHARACTER SET KANJISJIS'
                WHEN 4 THEN ' CHARACTER SET GRAPHIC'
                WHEN 5 THEN ' CHARACTER SET KANJI1'
                ELSE ''
             END
         ELSE ''
      END
;