SQL> ALTER TABLE tb_cons3 DROP COLUMN sal; ALTER TABLE tb_cons3 DROP COLUMN sal * ERROR at line 1: ORA-12991: column is referenced in a multi-column constraint --使用带有CASCADE CONSTRAINTS的DROP COLUMN 该表中的pk,f
报错:Feature not supported: INSERT on conflict contains un-unique column 问题原因:INSERT ON CONFLICT中的conflict条件使用了非主键字段。 解决方法:INSERT ON CONFLICT中的conflict条件只能使用主键。 报错:Feature not supported: UPDATE with shard keys ...
-- select the unique ages from the Customers tableSELECTDISTINCTageFROMCustomers; Run Code Here, the SQL command selects only the unique values of age from theCustomerstable. Syntax of SQL SELECT DISTINCT SELECTDISTINCTcolumn1, column2 ...FROMtable; Here, column1, column2, ...are the table...
customer Non_unique: 1 Key_name idx_fk_store_id Seq_in_index: 1 Column_name: store_id Collation: A Cardinality: 2 Sub_part: NULL Packed: NULL Null: Index_type: BTREE ... *** 3. row *** Table: customer Non_unique: 1 Key_name idx_fk_address_id Seq_in_index 1 Column_name...
A UNIQUE index creates a constraint such that all values in the index must be distinct. An error occurs if you try to add a new row with a key value that matches an existing row. If you specify a prefix value for a column in a UNIQUE index, the column values must be unique within...
mysql> SELECT t1.name AS '姓名',t1.teacher_id '老师ID' FROM student AS t1 WHERE id % 2 = 1 LIMIT 3; 8>.当多个表中有相同的字段名,且需要查询出来时,需要在SELECT_EXPR中使用tbl_name.column_name 来显视指定要查询哪个表的字段 9>.查看另外的数据库的表数据 ...
SELECT `column_name` FROM `table_name`; 1. 2. 使用SELECT COLUMN, COLUMN 查询多个列 当我们想要从一个表中查询多个列时,使用的 SELECT 语句与查询一个列时使用的语句相似,但是需要在 SELECT 关键字后给出多个列名,并且列名之间必须以逗号分隔。
1.select选择操作 标准模式为: select [all] coumns from tables [join joins] [where search_condition] [group by grouping_columns] [having search_condition] [order by sort_column] [ASC | DESC] 2.使用 AS 创建列的别名 column as alias_name ,... 3. ...
values (value1,value2,value3,...,valueN); column1,column2,...,columnN是要插入数据的列的名称。 只要按照与列相同的顺序指定值,就可以指定自己的列顺序。 在插入数据时,也可以将数据插入到特定列中。 五、update和delete语句 1、update语句
QtyAvailable, UnitPrice, InventoryValueFROMdbo.Products;-- Update values in the table.UPDATEdbo.ProductsSETUnitPrice =2.5WHEREProductID =1;-- Display the rows in the table, and the new values for UnitPrice and InventoryValue.SELECTProductID, QtyAvailable, UnitPrice, InventoryValueFROMdbo.Products...