如何从以下查询中选择行数？ - 甲骨文 SQL

Question

还需要在 Oracle SQL 中使用以下查询选择行/记录计数。我该怎么做呢？

SELECT DISTINCT t.OWNER AS TABLE_SCHEMA, t.Table_Name, c.COLUMN_NAME, c.DATA_TYPE, 
                ( 
                    SELECT CASE WHEN cons.CONSTRAINT_TYPE = 'P' THEN 'Primary Key' ELSE NULL END 
                    FROM SYS.all_cons_columns cols 
                        INNER JOIN SYS.all_constraints cons ON cons.constraint_name=cols.constraint_name AND cons.constraint_type = 'P' 
                    WHERE cols.Column_name=c.column_name AND cols.TABLE_NAME=c.TABLE_NAME AND cols.OWNER=c.OWNER 
                ) AS CONSTRAINT_TYPE, c.DATA_PRECISION, c.DATA_SCALE 
                FROM SYS.ALL_TABLES t 
                    INNER JOIN SYS.all_tab_columns c ON c.TABLE_NAME=t.TABLE_NAME AND c.OWNER=t.OWNER
                WHERE t.OWNER = 'MY_SCHEMA_NAME' AND t.Table_Name = 'MY_TABLE_NAME'

Answer 1

如果您可以接受估计行数（其准确性取决于每个表的统计信息的新鲜度），您可以只使用来自ALL_TABLES 的列NUM_ROWS：

SELECT 
    t.OWNER AS TABLE_SCHEMA, 
    t.Table_Name, 
    c.COLUMN_NAME, 
    c.DATA_TYPE, 
    t.NUM_ROWS, --> here
    ...
FROM all_tables t
INNER JOIN all_tab_columns c ...

请注意，DISTINCT 在这里似乎是多余的 - 您的查询会为表中的每一列生成一条记录。

如果您确实需要准确的计数，那么您可以使用内联查询 - 但您需要对表名进行硬编码：

SELECT 
    t.OWNER AS TABLE_SCHEMA, 
    t.Table_Name, 
    c.COLUMN_NAME, 
    c.DATA_TYPE, 
    (SELECT COUNT(*) FROM my_schema_name.my_table_name) no_rows,
    ...
FROM all_tables t
INNER JOIN all_tab_columns c ...
WHERE t.OWNER = 'MY_SCHEMA_NAME' AND t.Table_Name = 'MY_TABLE_NAME'

Answer 2

不确定您使用的是哪个 SQL，但您可能会将整个结果放入临时表中 喜欢

INTO temp temp_table_count WITH NO LOG;

SELECT COUNT(*) FROM temp_table_count;

Answer 3

https://www.oracletutorial.com/oracle-basics/oracle-private-temporary-table/参考

INSERT INTO ora$ppt_temp_table_count(ADD ALL COLUMNS HERE 
COMMASEPARATED)
SELECT col1, col2, col3
FROM source_table
WHERE condition; <-- your query

SELECT COUNT(*) FROM ora$ppt_temp_table_count;