notnull

SQL Column definition : default value and not null redundant?

由 两盒软妹~` 提交于 2019-11-27 09:49:12
问题 I've seen many times the following syntax which defines a column in a create/alter DDL statement: ALTER TABLE tbl ADD COLUMN col VARCHAR(20) NOT NULL DEFAULT "MyDefault" The question is: since a default value is specified, is it necessary to also specify that the column should not accept NULLs ? In other words, doesn't DEFAULT render NOT NULL redundant ? 回答1: DEFAULT is the value that will be inserted in the absence of an explicit value in an insert / update statement. Lets assume, your DDL

How to ignore null values using springframework BeanUtils copyProperties?

由 本小妞迷上赌 提交于 2019-11-27 06:55:36
I would like to know how to copy the properties from an Object Source to an Object Dest ignoring null values​​ using Spring Framework. I actually use Apache beanutils, with this code beanUtils.setExcludeNulls(true); beanUtils.copyProperties(dest, source); to do it. But now i need to use Spring. Any help? Thx a lot You can create your own method to copy properties while ignoring null values. public static String[] getNullPropertyNames (Object source) { final BeanWrapper src = new BeanWrapperImpl(source); java.beans.PropertyDescriptor[] pds = src.getPropertyDescriptors(); Set<String> emptyNames

How to ignore null values using springframework BeanUtils copyProperties?

由 允我心安 提交于 2019-11-26 12:14:20
问题 I would like to know how to copy the properties from an Object Source to an Object Dest ignoring null values​​ using Spring Framework. I actually use Apache beanutils, with this code beanUtils.setExcludeNulls(true); beanUtils.copyProperties(dest, source); to do it. But now i need to use Spring. Any help? Thx a lot 回答1: You can create your own method to copy properties while ignoring null values. public static String[] getNullPropertyNames (Object source) { final BeanWrapper src = new

MySQL SELECT only not null values

由 99封情书 提交于 2019-11-26 01:06:08
问题 Is it possible to do a select statement that takes only NOT NULL values? Right now I am using this: SELECT * FROM table And then I have to filter out the null values with a php loop. Is there a way to do: SELECT * (that are NOT NULL) FROM table ? Right now when I select * I get val1,val2,val3,null,val4,val5,null,null etc.... but I just want to get the values that are not null in my result. Is this possible without filtering with a loop? 回答1: You should use IS NOT NULL . (The comparison

MySQL SELECT only not null values

由 二次信任 提交于 2019-11-26 00:21:59
Is it possible to do a select statement that takes only NOT NULL values? Right now I am using this: SELECT * FROM table And then I have to filter out the null values with a php loop. Is there a way to do: SELECT * (that are NOT NULL) FROM table ? Right now when I select * I get val1,val2,val3,null,val4,val5,null,null etc.... but I just want to get the values that are not null in my result. Is this possible without filtering with a loop? You should use IS NOT NULL . (The comparison operators = and <> both give UNKNOWN with NULL on either side of the expression.) SELECT * FROM table WHERE
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