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所谓NULL-Aware Antijoin,根据Cost-Based Optimizer NULL-Aware Antijoin (文档 ID 1082123.1)可得知, NULL-Aware Antijoin 是一种功能,它试图解决与 NULL 值和子查询展开的各种问题。通常,如果子查询的连接条件可能为 NULLable,则子查询展开是不可能的。 而NULL-Aware Antijoin则可以按如下方式实现连接子查询展开后...
Annotation Type Nullable @Retention(value=RUNTIME) @Target(value={FIELD,METHOD}) public @interfaceNullable Annotation to define a property's default support for null as an allowed value. This can be overridden in aPropertyManagerimplementation if required. ...
2.sqlldr errors表示允许错误的行数,外部表用REJECT LIMIT UNLIMITED,这个功能上基本相同。 3.外部表的列不能指定为not nullable,这样就很难拒绝某列为空值的记录。 4.外部表不能使用continueif ,如果记录有换行的就比较难处理。
decode(t.nullable, 'N','NOT NULL', 'n','NOT NULL', NULL) col from dba_ind_columns i, dba_tab_columns t where i.table_name = upper('&Table_name') and owner = upper(nvl('&Owner',user)) and i.table_name = t.table_name ...
NULL是值的一种特殊状态，应转换为UNKNOWN值。任何与NULL的直接比较都将得到NULL作为结果。即使将NULL与...
// C# public struct OracleBoolean : IComparable, INullable, IXmlSerializable 猁璃 皿伕田奶母ODP.NET奪燴 砓俋玉仿奶田ODP.NET奪燴 砓玉仿奶田ODP.NET Core 失本件皮伉 Oracle.DataAccess.dll Oracle.ManagedDataAccess.dll Oracle.ManagedDataAccess.dll ...
I used to think that Oracle does not index a row when one of the column values is null. Some simple experimentation shows this to be not the case. I was able to run some queries unexpectedly accessing only indexes even though some columns were nullable (which of course was a pleasant sur...
所有列都可以包含null，因此需要将所有value types属性（即decimals、ints、DateTimes等）标记为nullable ...
SELECTt.table_name,t.num_rowsFROMuser_tables tWHERENUM_ROWSISNOTNULLANDTABLE_NAMENOTLIKE'%HIS%'ORDERBYNUM_ROWSDESC; image.png 七、方案二,获取表注释 SELECT t.COLUMN_ID, t.COLUMN_NAME, u.COMMENTS, t.DATA_TYPE , t.DATA_LENGTH , DECODE( t.NULLABLE, 'N', 'TRUE', 'FALSE'), t.TABLE...