sql alter column not null

UNIQUE constraint in the "id_p" column when the "Persons" table is created:Mysql:CREATE TABLE Persons (id_p int not null,lastname varchar (255) not null,firstname varchar (255), Address varchar (255), City VA Rchar (255), UNIQUE (Id_P) )SQL Server/oracle/ms Access:UNIQUE, LastName varchar (255) not

1. Error description1 queries executed, 0 success, 1 errors, 0 warnings query: Call Analyse_con (' 2015-01-01 00:00:00 ', ' 2016-01-01 00:00:00 ') error code: 1 048Column ' typeId ' cannot be null execution time : 0 sec Transmission Duration : 0 sec Total Time : 0.015 sec2. Cause of errorThe typeID field is int (8) and is not empty, but has null when inserting data, resulting in an error3. Solution

execution, so in the dynamic column based on the table, group fields, row to column fields, The value of these four row to column fixed required value to become the true meaning of the parameterization, you only need to set the parameter values according to their own environment, you can immediately see the effect (you can jump directly to: "Parameterized dynami

(usergender= ' male ' or usergender= ' female '); ALTER TABLE Users add constraint ck_users_userage check (userage>=18 and userage Delete constraint: ALTER TABLE Users drop constraint Df_users_usergender, ck_users_usergender (comma plus constraint to delete) bulk Add constraint:ALTER TABLE Users add constraint ck_users_usergender check (usergender= ' male ' or usergender= ' female ') Constraint ck_users_us

Tags: that is greater than stronggrouplov in insert get address When we want to query all result sets in SQL for which a column value is NULL, the query condition should write like thisSELECT * FROM table where field is nullInstead, use the SELECT * from table where field = NULL to not find the correct result. Then

Label:In creating a table table, we can specify that the column package does not contain a value, and that when a column does not contain a value, we can say that it contains null values. Determines whether the value is null and cannot be simply checked for =null. The SELECT

Partition_names| REBUILD PARTITION Partition_names| REPAIR PARTITION Partition_namesSQL statement format for adding new columns to a table after a column in MySQLALTER table ' database name '. ' Table name ' ADD COLUMN ' ProcID ' VARCHAR (6) DEFAULT ' after ' ppidchanged ';In MySQL, if the table name, database name, column name, you add, modify, update, you need

Tags: isnull def replace img name XML for data archiveOne or more rows into a column (and separated by ",")Table Name: ATable data:Desired Query Results:Query statement:Select Name, value = (STUFF (select ', ' + value from A WHERE name = Test.name forThe Ps:stuff statement is to get rid of the first "comma"Attached stuff usage: (replace three characters with the following characters f

indexed. Therefore, some qualified data may not be found during query. In count (expr), nvl (column name, 0) is used for processing and then query.G. The sorting time is larger than other data (the index is sorted in descending order by default, small → large), so the NULL value is always at the end.Is null and is not null