Learn about oralce and what to write

Learn about oralce and what to write

1. query statement select * from TF_ B _TERM_PREPMG_LOG; select * from TD_M_TERM_PRICE; select * from TF_ B _CEN_TERM_MANAGER_LOG, Region; // query select * from region together with two tables; select * from TF_ B _CEN_TERM_MANAGER_LOG; select log_id * (1 + 0.1) newLog_id from TF_ B _CEN_TERM_MANAGER_LOG; // you can increase the log_id by 10% and use newlog_id to display select distinct log_id from TF_ B _CEN_TERM_MANAGER_LOG; // distinct: filter out data with the same keyword select * from TF_ B _CEN_TERM_MANAGER_LOG where log_id is null; // when the query condition is that a field is null, the statement select * from TF_ B _CEN_TERM_MANAGER_LOG where log_id is not null; select * from TF_ B _CEN_TERM_MANAGER_LOG where log_id> 300 order by log_id; // order by default, select * from TF_ B _CEN_TERM_MANAGER_LOG where log_id> 300 order by log_id desc; // order by is in ascending order by default. If you need to sort in descending order, add descselect * from TF_ B _CEN_TERM_MANAGER_LOG where log_id> 300 order by log_id, res_trade_id desc; // order by can be arranged with multiple parameters. The principle is to finish the first order and sort the second. // the commonly used function select count (*) from TF_ B _CEN_TERM_MANAGER_LOG; // count (*) select avg (log_id) from TF_ B _CEN_TERM_MANAGER_LOG; // average avg (keyword) select min (log_id) from TF_ B _CEN_TERM_MANAGER_LOG; // select max (log_id) from TF_ B _CEN_TERM_MANAGER_LOG; // select sum (log_id) from TF_ B _CEN_TERM_MANAGER_LOG; // calculate the records of a field in the table and select avg (log_id) from TF_ B _CEN_TERM_MANAGER_LOG group by log_id; // associate all records with the same logid, select avg (log_id) from TF_ B _CEN_TERM_MANAGER_LOG group by log_id having avg (log_id)>-1; // having statement is usually used together with group.