uniquekey constraint requires that every value in a column or set of columns beunique. No rows of a table may have duplicate values in a column (the uniquekey) or set of columns (the composite unique key) with a unique key constraint. Note: Theterm key refers only to the columns define...
Because the database enforces a unique constraint byimplicitly creating or reusing an index on the key columns, --数据库在创建unique constraint的同时,强制创建或者重用列上的索引。如果之前列上没有索引,那么强制创建的索引是unique index,如果列上已经存在索引,就重用之前的索引。 Uniquekey...
uniquekey constraint requires that every value in a column or set of columns beunique. No rows of a table may have duplicate values in a column (the uniquekey) or set of columns (the composite unique key) with a unique key constraint. Note: Theterm key refers only to the columns define...
that can sometimes speed data access. By creating an index on one or more columns of a table, you gain the ability in some cases to retrieve a small set of randomly distributed rows from the table. Indexes are one of many means of reducing disk I/O. ...
constraint_name TEXT 约束的名称。 table_name TEXT 约束所属表的名称。 column_name TEXT 约束中引用的列的名称。 position SMALLINT 列在对象定义中的位置。 3.8.3.10 dba_ind_columns 描述了数据库中所有表和集群的所有索引的列。它的列与 ALL_IND_COLUMNS 中的列相同。 名称类型说明 index_owner name 索引...
SQL statements, 15-12, 15-20 partial backups, 29-26 PARTITION clause, 11-63 partition views, 11-11 partitioning columns, 11-13 LOBs DML locks, 11-45 maintenance operations, 11-56 tables with LOB columns, 11-37 partitions, 11-2, 11-11 advantages of, 11-5, 11-7 ...
java.sql.SQLIntegrityConstraintViolationException: ORA-00001: unique constraint (USR_JXZX_DSJKF_MODEL.SYS_C001362707) violated 主键不一致,须联系数据中心修改 经DataX智能分析,该任务最可能的错误原因是: com.alibaba.datax.common.exception.DataXException: Code:[Framework-14], Description:[DataX传输脏数据...
PGXC_INSTR_UNIQUE_SQL PGXC_LOCK_CONFLICTS PGXC_LWLOCKS PGXC_MEMORY_DEBUG_INFO PGXC_NODE_ENV PGXC_NODE_STAT_RESET_TIME PGXC_OBS_IO_SCHEDULER_STATS PGXC_OBS_IO_SCHEDULER_PERIODIC_STATS PGXC_OS_RUN_INFO PGXC_OS_THREADS PGXC_POOLER_STATUS PGXC_PREPARED_XACTS PGXC_REDO_STAT PGX...
SQL> select OWNER,CONSTRAINT_NAME ,COLUMN_NAME,POSITION from User_cons_columns where TABLE_NAME='DEPT'; How to find constraint by name in Oracle select CONSTRAINT_NAME ,INDEX_NAME,CONSTRAINT_TYPE,Search_condition,R_CONSTRAINT_NAME R_NAME from user_constraints where CONSTRAINT_NAME='&1' ...
Oracle allows multiple BLOB and CLOB columns per table. BLOBS and CLOBS may or may not be stored in the row depending on their size. If the Microsoft SQL Server TEXT column is such that the data never exceeds 4000 bytes, convert the column to an Oracle VARCHAR2 data type column instead...