SELECT element FROM (VALUES ( ARRAY[1,2,3]) ) as t(element)。输出结果为3行,分别是1、2、3.。 其他SQL语法 除了SELECT语法,还有其他的语法例如INSERT/CREATE 等DDL语句。 小结 本文介绍了SQL和查询相关的一些核心语法规则,有助于读者了解SQL能够完成哪些方面的计算。在后续的章节中,我们继续了...
It turned out that many entries in the table 1 and table 2 had string_field column with NULL values. I thought that JOIN would keep records with NULL values because NULL is equal to NULL, isn’t it? Then I tried: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 SELECTNULL=NULL It ...
报错:failed to import foreign schema from odps:Table not found -xxx 问题原因:查询的表在MaxCompute中不存在。 解决方法:前往MaxCompute确认表是否存在。 ERRCODE_UNIQUE_VIOLATION或者pk violates 报错:Update row with Key (id)=(xxxx) multiple times或者duplicate key value violates unique constraint ...
9、select into SELECT INTO 语句从一个表复制数据,然后把数据插入到另一个新表中。 注意: MySQL 数据库不支持 SELECT ... INTO 语句,但支持 INSERT INTO ... SELECT select into语法: 1 2 3 4 5 6 7 8 9 SELECT* INTOnewtable [INexternaldb] FROMtable1; 或: SELECTcolumn_name(s) INTOnewtable...
mysql>insert intotest1(id,card_no,name,c1)values(1,'1000000001','abc','a');ERROR1062(23000):Duplicate entry'1'forkey'test1.PRIMARY' 加上ignore选项后,结果如下: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 mysql>select*from test1;+---+---+---+---+|id|card_no|name|c1|+--...
$sql="INSERT into users (username,password,email) VALUES('$username','$password','$email')"; $result = mysql_query("INSERT INTO users VALUES ('duplicate')"); if (!$result) { echo "Enter a different value"; } else { echo "Save successful."; ...
在表上创建一个唯一的索引。不允许使用重复的值:唯一的索引意味着两个行不能拥有相同的索引值。Creates a unique index on a table. Duplicate values are not allowed: CREATE UNIQUE INDEX index_name ON table_name (column_name) 1. 2. 注释:用于创建索引的语法在不同的数据库中不一样。因此,检查数据库...
CREATE TABLE TestBatch (ColA INT PRIMARY KEY, ColB CHAR(3)); GO INSERT INTO TestBatch VALUES (1, 'aaa'); INSERT INTO TestBatch VALUES (2, 'bbb'); INSERT INTO TestBatch VALUES (1, 'ccc'); -- Duplicate key error. GO SELECT * FROM TestBatch; -- Returns rows 1 ...
SELECT DISTINCT vs SELECT TheSELECT DISTINCTstatement is used when you want to return only unique (distinct) values in the result set. Whereas, a regularSELECTstatement without theDISTINCTkeyword retrieves all rows from the specified columns, including duplicate values. ...
values (1,'Deal for John Doe'); 然后,创建一个名为usp_report_error的新存储过程,该存储过程用于在CATCH块中用于报告错误的详细信息: CREATE PROC usp_report_error AS SELECT ERROR_NUMBER() AS ErrorNumber ,ERROR_SEVERITY() AS ErrorSeverity ,ERROR_STATE() AS ErrorState ,ERROR_LINE () AS ...