1.查询用户的所有表
2.查询表关系，外键，主键,约束条件
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oracle数据库：
String reSql = "SELECT A.TABLE_NAME AS P_TABLE_NAME,B.COLUMN_NAME AS P_COLUMN_NAME,C.TABLE_NAME AS F_TABLE_NAME,"+
"D.COLUMN_NAME AS F_COLUMN_NAME FROM USER_CONSTRAINTS A LEFT JOIN USER_CONS_COLUMNS B ON A.CONSTRAINT_NAME=B.CONSTRAINT_NAME "+
"LEFT JOIN USER_CONSTRAINTS C ON C.R_CONSTRAINT_NAME = A.CONSTRAINT_NAME LEFT JOIN USER_CONS_COLUMNS D ON C.CONSTRAINT_NAME= "+
"D.CONSTRAINT_NAME WHERE A.CONSTRAINT_TYPE=‘P‘ AND NVL(C.TABLE_NAME,‘ ‘)!=‘ ‘ AND NVL(D.COLUMN_NAME,‘ ‘)!=‘ ‘ ORDER BY A.TABLE_NAME";
String rsSql = "SELECT COL.COLUMN_NAME FROM USER_CONSTRAINTS CON,USER_CONS_COLUMNS COL "
+ "WHERE CON.CONSTRAINT_NAME = COL.CONSTRAINT_NAME AND CON.CONSTRAINT_TYPE=‘P‘ AND COL.TABLE_NAME=‘"
+ tableName + "‘ ORDER BY COLUMN_NAME";
String sql = "(select TABLE_NAME AS name,‘U‘ as xtype from ALL_TABLES where OWNER IN (‘DBO‘,‘VHBIYF‘) "+
"union all "+
"select VIEW_NAME AS name,‘V‘ as xtype from all_views where owner IN (‘DBO‘,‘VHBIYF‘) ) result";
return sql;
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sqlserver：
String rsSql = "SELECT C.NAME AS COLUMN_NAME FROM SYSINDEXES I JOIN SYSINDEXKEYS K ON I.ID=K.ID AND I.INDID=K.INDID "
+ "JOIN SYSOBJECTS O ON I.ID = O.ID JOIN SYSCOLUMNS C ON I.ID=C.ID AND K.COLID=C.COLID "
+ "WHERE O.XTYPE=‘U‘ AND EXISTS(SELECT 1 FROM SYSOBJECTS WHERE XTYPE=‘PK‘ AND NAME=I.NAME) "
+ "AND O.NAME=‘"+tableName+"‘ ORDER BY O.NAME,K.COLID";
String reSql="select oMain.name AS P_TABLE_NAME,MainCol.name AS P_COLUMN_NAME,oSub.name AS F_TABLE_NAME,SubCol.name AS F_COLUMN_NAME "+
"from sys.foreign_keys fk JOIN sys.all_objects oSub ON (fk.parent_object_id = oSub.object_id) JOIN sys.all_objects oMain "+
"ON (fk.referenced_object_id = oMain.object_id) JOIN sys.foreign_key_columns fkCols ON (fk.object_id = fkCols.constraint_object_id) "+
"JOIN sys.columns SubCol ON (oSub.object_id = SubCol.object_id AND fkCols.parent_column_id = SubCol.column_id) JOIN sys.columns MainCol "+
"ON (oMain.object_id = MainCol.object_id AND fkCols.referenced_column_id = MainCol.column_id)";
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