comcast t1

The syntax for merge is as follows:MERGE [hint] into [schema.] table [T_alias] USING [schema.] {Table | view | subquery} [T_alias] On (condition) when matched and merge_update_clause when not matched then merge_insert_clause;What is merge and how is it used? Let's first look at a simple requirement:The requirement is to update the data from the T1 table to the T2 table, and if the name of the T2 table already exists in the

:02:02 ') Insert into [Table] (Y, X) VALUES (' BBB ', ' 2007-03-03 03:03:03 ') Insert into [Table] (Y, X) VALUES (' CCC ', ' 2007-01-01 01:01:01 ') Insert into [Table] (Y, X) VALUES (' AAA ', ' 2007-01-01 01:01:01 ') Insert into [Table] (Y, X) VALUES (' CCC ', ' 2007-03-03 03:03:03 ') Insert into [Table] (Y, X) VALUES (' DDD ', ' 2007-01-01 01:01:01 ') Insert into [Table] (Y, X) VALUES (' DDD ', ' 2007-02-02 02:02:02 ') Insert into [Table] (Y, X) VALUES (' DDD ', ' 2007-03-03 03:03:03 ')

In Oracle, how does one obtain user table information and other details ?, Oracle acquisition 1. Get the User Name of the current user SELECT USERNAME FROM USER_USERS; 2. Obtain the names of all tables under a user. SELECT TABLE_NAME FROM ALL_TABLES where owner = 'username'; -- case sensitive 3. Obtain the details of a table under the current user. Select t. TABLE_NAME, -- table name T. COLUMN_NAME, -- field name T. DATA_TYPE, -- field type T. DATA_LENGTH, -- length T. NULLABLE -- whether it is

Many data blocks in the HWL are non-data, but the data blocks in the high-water line need to be scanned during full table scanning. That is to say, oracle has to do a lot of useless work! Therefore, oracle provides the shrink space fragment function. For indexes, rebuild online can be used for fragment. Generally, DBAs that frequently perform DML operations should be regularly maintained, and statistics should be updated in a timely manner!I. Prepare test dataUse the HR user to create table

this object. as a result, access by other threads to all the synchronized code parts of the object is temporarily blocked. 5. The above rules apply to other Object locks. Example: 1. When two concurrent threads access the synchronized (this) synchronization code block of the same object, only one thread can be executed within a time period. the other thread must wait until the current thread finishes executing this code block before executing this code block. Package ths; Public class thread1 i

blocked by other threads. The third example also applies to other synchronized code blocks. That is, when a thread accesses a synchronized (this) synchronization code block of object, it obtains the object lock of the objects. As a result, access to all of the synchronization code portions of the object object by other threads is temporarily blocked. The above rules apply to other object locks as well. An example is provided: First, when two concurrent threads access the synchronized (this)

A few knowledge points about where and on conditions in the left join: 1. Multiple table LEFT join is a temporary table that is generated and returned to the user 2.where condition is filtered for the last generated temporary table, filtering out records that do not meet the Where condition. is really non-conforming on the filter out. The 3.on condition is conditional filtering on the right table of the left join, but still returns all rows from the table in the right, and the fill null 4.on

Oracle Execution Plan (3)-join base of two tables 1 formula: Base join selection rate * filter condition 1 base + filter condition 2 base join selection rate (num_rows (Table 1) -num_nulls (Table 1 connection field) num_rows (table 1) * (num_rows (table 2)-num_nulls (Table 2 connection field) num_rows (table 2 )) Oracle Execution Plan (3)-Two-table join base 1 formula: base = connection selection rate * filtering condition 1 base + filtering condition 2 base join selection rate = (num_rows (Tabl

a partition is being locked in any mode, and all of its parents be locked in ' S ' mode.Based on this, the lock acquired for a operation is as follows: Hive Command Locks acquired Select: T1 Partition P1 S on T1, T1. P1 INSERT into T2 (partition P2) Select: T1 Partit

more information.Label: mydataUUID: 54161207-74c5-4851-b945-70c510a914c1Node size: 16384Sector size: 4096Filesystem size: 4.00GiBBlock group profiles: Data: RAID0 409.50MiB Metadata: RAID1 204.75MiB System: RAID1 8.00MiBSSD detected: noIncompat features: extref, skinny-metadataNumber of devices: 4Devices: ID SIZE PATH 1 1.00GiB /dev/sdb5 2 1.00GiB /dev

SQL Profile provides other information except system statistics and object (table and index) statistics for an SQL statement, such as the running environment and more accurate statistics, to help the optimizer select a more suitable execution plan for SQL statements.SQL Profiles can be said to be the evolution of Outlines. The functions that Outlines can implement can also be fully implemented by SQL Profiles, while SQL Profiles have optimizations that Outlines do not have. The most important ar

namespacestd;BOOLmap1[1005][1005];intrem[1005][1005];intfrem[1005][1005];intn,m;intsi,sj,fi[1000006],fj[1000006];intcou;BOOLJudgeintXintYinttemp) { if(x0|| y0|| x>n| | Y>M)return 0; if(!Map1[x][y])return 0; if(Rem[x][y])return 0; if(frem[x][y]>-1temp>=Frem[x][y])return 0; return 1;}BOOLJudge1 (intXinty) { if(x0|| y0|| x>n| | Y>M)return 0; if(!Map1[x][y])return 0; if(frem[x][y]!=-1) return 0; return 1;}intSlove () {Queueint>que; inttemp,t1