CREATE INDEX index_emp_name on emp1(name); ALTER TABLE emp2 ADD UNIQUE INDEX index_bank_num(band_num); -- 删除索引 语法:DROP INDEX 索引名 on 表名 DROP INDEX index_emp_name on emp1; DROP INDEX bank_num on emp2; 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15...
#1.创建 单值索引:一个索引包含了一个列 CREATE INDEX job_index ON emp(job) #创建 唯一索引 #alter table emp add unique(deptno)报错,deptno的值重复啦 ALTER TABLE emp ADD UNIQUE(ename) #创建 复合索引:最左特性 ALTER TABLE emp ADD INDEX many_index(ename,job,hiredate) #2.查看索引 SHOW INDEX ...
* The special negative case allows us to cope with columns that are * unique (stadistinct = -1) or nearly so (for example, a column in which * non-null values appear about twice on the average could be represented * by stadistinct = -0.5 if there are no nulls, or -0.4 if 20% ...
ERROR: duplicate key value violates unique constraint "t_pk" I suppose that it could reflect that fact that the call togen_random_uuid()returned a previously-seen value. But the probability that this might happen is supposed to be vanishingly small. And my program calledgen_random_uuidonly ...
elog(ERROR, "could not lookup '%s' tuple desc", typname); } #define RVSZ 8192 /* Max length of header element */ /** * Convert a string of headers separated by newlines/CRs into an * array of http_header tuples.*/
(For example, in psql you could issue \d+ pg_stat_activity.) The access functions for per-database statistics take a database OID as an argument to identify which database to report on. The per-table and per-index functions take a table or index OID. The function...
ALTERTABLEtable_nameADDCONSTRAINTconstraint_nameconstraint_definition;ALTERTABLEtable_nameDROPCONSTRAINTIFEXISTconstraint_name;ALTERTABLEtable_nameALTERCOLUMNcolumn_nameDROPNOTNULL; Example ALTER TABLE example ADD CONSTRAINT unique_constraint UNIQUE (a, c); ...
In subscriber log I could see the following statement executed 015_stream.pl line 255: $node_subscriber->safe_psql('postgres', "CREATE UNIQUE INDEX idx_tab on test_tab_2(a)"); With the following log content from 015_stream_subscriber.log: ...
create table t1(a int, b int, c int not null, primary key(a, b)); \d+ t1 ERROR: operator is not unique: smallint[] <@ smallint[] LINE 8: coalesce(NOT ARRAY[at.attnum] <@ (SELECT conkey FROM pg_cata... ^ HINT: Could not choose a best candidate operator. You might need...
pgsql计算的hash值和java不一样 hash unique oracle 一.索引介绍 1.1索引的创建语法: CREATE UNIUQE | BITMAP INDEX . ON . ( | ASC | DESC, | ASC | DESC,...)TABLESPACE STORAGE LOGGING | NOLOGGINGCOMPUTE STATISTICSNOCOMPRESS | COMPRESSNOSORT | REVERSEPARTITION | GLOBAL PARTITION...