我如何從查詢中的兩個表中獲取數據？

Question

我想從兩個表中獲取所有數據，並將其轉換為StringBuffer，但是查詢有問題。 我不知道該怎么稱呼。

該方法將顯示由他的培訓計划創建的用戶。 該計划將有兩種。 例如，在FBW_TABLE_SET_A_CHEST中，用戶選擇了名為“擠壓杠鈴”的練習，在FBW_TABLE_SET_B_CHEST中，用戶選擇了名為“擠壓杠鈴”的練習。

這是表的調用方式

private static final String FBW_TABLE_NAME_SET_A = "FbwSetA";
private static final String FBW_TABLE_SET_A_CALF = "calfExerciseSetA";
private static final String FBW_TABLE_SET_A_LEGS = "legsExerciseSetA";
private static final String FBW_TABLE_SET_A_BACK = "backExerciseSetA";
private static final String FBW_TABLE_SET_A_SHOULDERS = "shouldersExerciseSetA";
private static final String FBW_TABLE_SET_A_BICEPS = "bicepsExerciseSetA";
private static final String FBW_TABLE_SET_A_TRICEPS = "tricepsExerciseSetA";
private static final String FBW_TABLE_SET_A_CHEST = "chestExerciseSetA";
private static final String FBW_TABLE_SET_A_ABS = "absExerciseSetA";
private static final String FBW_TABLE_SET_A_FOREARM = "forearmExerciseSetA";

private static final String FBW_TABLE_NAME_SET_B = "FbwSetB";
private static final String FBW_TABLE_SET_B_CALF = "calfExerciseSetB";
private static final String FBW_TABLE_SET_B_LEGS = "legsExerciseSetB";
private static final String FBW_TABLE_SET_B_BACK = "backExerciseSetB";
private static final String FBW_TABLE_SET_B_SHOULDERS = "shouldersExerciseSetB";
private static final String FBW_TABLE_SET_B_BICEPS = "bicepsExerciseSetB";
private static final String FBW_TABLE_SET_B_TRICEPS = "tricepsExerciseSetB";
private static final String FBW_TABLE_SET_B_CHEST = "chestExerciseSetB";
private static final String FBW_TABLE_SET_B_ABS = "absExerciseSetB";
private static final String FBW_TABLE_SET_B_FOREARM = "forearmExerciseSetB";

這是我通過db.execSQL（..）“創建”它的方式

db.execSQL("create table " + FBW_TABLE_NAME_SET_A + " (ID INTEGER PRIMARY KEY AUTOINCREMENT," + FBW_TABLE_SET_A_CALF + " TEXT," + FBW_TABLE_SET_A_LEGS + " TEXT," + FBW_TABLE_SET_A_BACK + " TEXT," + FBW_TABLE_SET_A_SHOULDERS + " TEXT," + FBW_TABLE_SET_A_BICEPS + " TEXT," + FBW_TABLE_SET_A_TRICEPS + " TEXT," + FBW_TABLE_SET_A_CHEST + " TEXT," + FBW_TABLE_SET_A_ABS + " TEXT," + FBW_TABLE_SET_A_FOREARM + " TEXT)");
    db.execSQL("create table " + FBW_TABLE_NAME_SET_B + " (ID INTEGER PRIMARY KEY AUTOINCREMENT," + FBW_TABLE_SET_B_CALF + " TEXT," + FBW_TABLE_SET_B_LEGS + " TEXT," + FBW_TABLE_SET_B_BACK + " TEXT," + FBW_TABLE_SET_B_SHOULDERS + " TEXT," + FBW_TABLE_SET_B_BICEPS + " TEXT," + FBW_TABLE_SET_B_TRICEPS + " TEXT," + FBW_TABLE_SET_B_CHEST + " TEXT," + FBW_TABLE_SET_B_ABS + " TEXT," + FBW_TABLE_SET_B_FOREARM + " TEXT)");

總而言之：該方法應該從兩個表中獲取所有數據，然后強制轉換為StringBuffer並顯示由他的培訓計划創建的用戶。

Answer 1

使用UNION復合運算符。

SQL代碼是這樣的：

SELECT col1, col2 from table1 UNION SELECT col1, col2 from table2

Answer 2

db.execSQL("SELECT * FROM " + FBW_TABLE_NAME_SET_A + 
"UNION" +
"SELECT * FROM " + FBW_TABLE_NAME_SET_B);

這應該為您提供兩個表的所有非重復行。