从远程Oracle服务器上同步复制数据到本地备份库 create or replace PROCEDURE SYNC_DATA_FROM_DBLINK_DB ASBEGIN DECLARE CU
从远程Oracle服务器上同步复制数据到本地备份库
create or replace PROCEDURE "SYNC_DATA_FROM_DBLINK_DB" AS
BEGIN
DECLARE
CURSOR c_TabNames IS
SELECT TNAME FROM TAB;
v_TabName c_TabNames%ROWTYPE;
v_SQL VARCHAR2(500);
v_rowcount NUMBER;
v_rc NUMBER:=0;
v_tab NUMBER :=0;
BEGIN
Dbms_Output.put_line(to_char(SYSDATE,'yy-mm-dd hh24:mi:ss')||' 开始从远程的TEST2实例导入表.');
FOR v_TabName in c_TabNames LOOP
v_SQL := 'DELETE '||v_TabName.TNAME;
EXECUTE IMMEDIATE v_sql;
v_sql := 'INSERT INTO '|| v_tabname.TNAME||' SELECT * FROM '|| v_tabname.TNAME||'@TEST2';
EXECUTE IMMEDIATE v_sql;
COMMIT;
v_SQL :='SELECT COUNT(*) FROM '|| v_tabname.TNAME;
EXECUTE IMMEDIATE v_sql INTO v_rowcount;
v_tab := v_tab +1;
v_rc := v_rc + v_rowcount;
END LOOP;
Dbms_Output.put_line(to_char(SYSDATE,'yy-mm-dd hh24:mi:ss')||' 导入完成,,共导入表'||to_char(v_tab)||'张,总记录数'||to_char(v_rc)||'条记录。');
END;
END SYNC_DATA_FROM_DBLINK_DB;

MySQL functions can be used for data processing and calculation. 1. Basic usage includes string processing, date calculation and mathematical operations. 2. Advanced usage involves combining multiple functions to implement complex operations. 3. Performance optimization requires avoiding the use of functions in the WHERE clause and using GROUPBY and temporary tables.

Efficient methods for batch inserting data in MySQL include: 1. Using INSERTINTO...VALUES syntax, 2. Using LOADDATAINFILE command, 3. Using transaction processing, 4. Adjust batch size, 5. Disable indexing, 6. Using INSERTIGNORE or INSERT...ONDUPLICATEKEYUPDATE, these methods can significantly improve database operation efficiency.

In MySQL, add fields using ALTERTABLEtable_nameADDCOLUMNnew_columnVARCHAR(255)AFTERexisting_column, delete fields using ALTERTABLEtable_nameDROPCOLUMNcolumn_to_drop. When adding fields, you need to specify a location to optimize query performance and data structure; before deleting fields, you need to confirm that the operation is irreversible; modifying table structure using online DDL, backup data, test environment, and low-load time periods is performance optimization and best practice.

Use the EXPLAIN command to analyze the execution plan of MySQL queries. 1. The EXPLAIN command displays the execution plan of the query to help find performance bottlenecks. 2. The execution plan includes fields such as id, select_type, table, type, possible_keys, key, key_len, ref, rows and Extra. 3. According to the execution plan, you can optimize queries by adding indexes, avoiding full table scans, optimizing JOIN operations, and using overlay indexes.

Subqueries can improve the efficiency of MySQL query. 1) Subquery simplifies complex query logic, such as filtering data and calculating aggregated values. 2) MySQL optimizer may convert subqueries to JOIN operations to improve performance. 3) Using EXISTS instead of IN can avoid multiple rows returning errors. 4) Optimization strategies include avoiding related subqueries, using EXISTS, index optimization, and avoiding subquery nesting.

Methods for configuring character sets and collations in MySQL include: 1. Setting the character sets and collations at the server level: SETNAMES'utf8'; SETCHARACTERSETutf8; SETCOLLATION_CONNECTION='utf8_general_ci'; 2. Create a database that uses specific character sets and collations: CREATEDATABASEexample_dbCHARACTERSETutf8COLLATEutf8_general_ci; 3. Specify character sets and collations when creating a table: CREATETABLEexample_table(idINT

To safely and thoroughly uninstall MySQL and clean all residual files, follow the following steps: 1. Stop MySQL service; 2. Uninstall MySQL packages; 3. Clean configuration files and data directories; 4. Verify that the uninstallation is thorough.

Renaming a database in MySQL requires indirect methods. The steps are as follows: 1. Create a new database; 2. Use mysqldump to export the old database; 3. Import the data into the new database; 4. Delete the old database.


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