In Oracle, a column alias is a temporary column name that you assign to a column or expression during a query’s execution. When youquery data from a table, Oracle displays the column headings using the table’s
---merge into 9i新特性 更新表,以及刷存量数据是效率最高 MERGE INTO table_name alias1 USING (table|view|sub_query) alias2 ON (join condition) WHEN MATCHED THEN UPDATE table_name SET col1 = col_val1, col2 = col_val2 WHEN NOT MATCHED THEN INSERT (column_list) VALUES (column_values);...
CREATEORREPLACEPROCEDURETESTAS--表名N_TABLE_NAME VARCHAR2(32);--逗号数量,用于循环SIGNSINT;--逗号数量最大值,用于判断是否加ANDSI_MAXINT;--主查询别名ALIAS VARCHAR2(16);--副查询别名头F_ALI VARCHAR2(16);--用于存放被查询表数量NUMINT;--当前循环取到的值CURRENT_VALUE VARCHAR2(32);--拼接好的...
从语法解析规则文件来看,似乎是可以区分的,然后解析一下这条SQL: select*fromt1leftjoint2ont1.id=t2.ids;^Z(sql_script(unit_statement(data_manipulation_language_statements(select_statement(select_only_statement(subquery(subquery_basic_elements(query_blockselect(selected_list*)(from_clausefrom(table_ref_l...
select [distinct] {*,column [alias],...} from table 注:[]括起来的内容代表可有可无 * 代表所有列 distinct关键字只能跟在select关键字之后 select 子句后边指定要查询的列 from 子句后边跟要查询的表 My name is first_name.last_name; 2.select语句可以对指定的列的所有值进行算术运算。
merge法--适合与两张表的关联查询MERGEINTOtable_name alias1USING(table|view|sub_query) alias2ON(joincondition)WHENMATCHEDTHENUPDATEtable_nameSETcol1=col_val1WHENNOTMATCHEDTHENINSERT(column_list)VALUES(column_values);--例:mergeintoAccount t1using(select'3'AccountID,'肖文博'AccountNamefromdual) t2on...
網路別名實質上是指向在建立資料庫時設定之遠端 SID 或服務名稱的指標;不同的 Oracle 版本與產品中所使用的稱呼各有不同,包括網路服務名稱 (Net Service Name) 和 TNS 別名 (TNS Alias)。 您登入時,SQL*Plus 會提示以「Host String」參數輸入這個別名。 選取網路通訊協定 選取您要支援的適當通訊協定。 大...
s.username user_name, s.fixed_table_sequence activity_meter, ''' query, 0 memory, 0 max_memory, 0 cpu_usage, s.sid, s.serial# serial_num from v$session s, v$process p where s.paddr=p.addr and s.type = ''USER'' order by s.username, s.osuser2)根据v.sid查看对应连接的资源占用...
Connect to an on-premises Oracle database from Power Query Desktop To make the connection, take the following steps: Select theOracle databaseoption in the connector selection. Specify the Oracle net service name/TNS alias or Easy Connect (Plus) connection string to connect to inServer. Easy ...
The first column your view should select is the ROWID pseudo-column for the root table, and the view should alias it to ROW_ID. Your view should then include all of the columns in the root table, including the WHO columns, and denormalized foreign key information. Tip: You only need to...