BigQuery脚本-在插入之前动态投射行

如何解决BigQuery脚本-在插入之前动态投射行

• 我有表A和表B。
• 在表A中，所有列都是字符串
• 在表B中，我有与列A中相同的列，但它们的实数 类型。

我想使用bq脚本编写过程来获取A行，使用表B的架构转换其列值，然后将其插入到B中。

例如：在表A和B中，我有'score'列，它是A中的字符串，而B中的NUMERIC，我的目标是从A中获取，如果可能的话将其转换为数字，然后将其插入B． 为了动态地执行此操作，我正在收集B的架构以了解要转换的内容。

对不起，我的英语，英语不是我的母语。

    BEGIN
    
    DECLARE offset_ INT64 DEFAULT 1; -- OFFSET starts in 1 BASED on ROW NUMBER ()
    DECLARE limit_ INT64 DEFAULT 500; -- Size of the chunks to be processed
    DECLARE size_ INT64 DEFAULT 1000; -- Size of the data (used for the condition in the WHILE loop)
    
    DECLARE int_keys ARRAY<STRING>;
    DECLARE num_keys ARRAY<STRING>;
    DECLARE bool_keys ARRAY<STRING>;
    DECLARE str_keys ARRAY<STRING>;
    DECLARE date_keys ARRAY<STRING>;
    
    
    set int_keys = (SELECT ARRAY_AGG(column_name) FROM B_dataset.informatION_SCHEMA.COLUMNS
    where table_name = B and data_type = 'INT64');
    set num_keys = (SELECT ARRAY_AGG(column_name) FROM B_dataset.informatION_SCHEMA.COLUMNS
    where table_name = B and data_type = 'NUMERIC');
    set bool_keys = (SELECT ARRAY_AGG(column_name) FROM B_dataset.informatION_SCHEMA.COLUMNS
    where table_name = B and data_type = 'BOOL');
    set str_keys = (SELECT ARRAY_AGG(column_name) FROM B_dataset.informatION_SCHEMA.COLUMNS
    where table_name = B and data_type = 'STRING');
    set date_keys = (SELECT ARRAY_AGG(column_name) FROM B_dataset.informatION_SCHEMA.COLUMNS
    where table_name = B and data_type = 'TIMESTAMP');
    
    CREATE TEMPORARY TABLE IF NOT EXISTS stg_records AS (
      SELECT *,ROW_NUMBER() OVER()  row_number
        FROM (select * from A_dataset.A )
    );
    
    
    
    WHILE loop
    WHILE offset_ < size_ DO
    
        INSERT INTO B_dataset.B (
#for example,here I would like to get the columns that I have to convert to integer and cast them
        SELECT int_keys FROM stg_records WHERE row_number BETWEEN offset_ AND offset_ + limit_ - 1
        UNION ALL
        SELECT num_keys FROM stg_recordsWHERE row_number BETWEEN offset_ AND offset_ + limit_ - 1
        UNION ALL
        SELECT bool_keys FROM stg_recordsWHERE row_number BETWEEN offset_ AND offset_ + limit_ - 1
        UNION ALL
        SELECT str_keys FROM stg_records WHERE row_number BETWEEN offset_ AND offset_ + limit_ - 1
        UNION ALL
        SELECT date_keys FROM stg_records WHERE row_number BETWEEN offset_ AND offset_ + limit_ - 1
        );
    
    
        SET offset_ = offset_ + limit_;
    
    END WHILE;
    END;