创建 sqlite 数据库时使用“ ”的正确方法

Question

I am confused about why at some places it is necessary to place " " at some distance from the text. For Eg In "CREATE TABLE ", the " is placed at some distance from TABLE.

String DATABASE_TABLE_CREATION = "CREATE TABLE "+ UtilConstants.TABLE_NAME+"(" + UtilConstants.KEY_ID
        + " Integer PRIMARY KEY," + UtilConstants.KEY_NAME + " TEXT," +
        UtilConstants.KEY_PHONENUMBER + "TEXT" +  ")";
db.execSQL(DATABASE_TABLE_CREATION);

Answer 1

Basically by writing this code

String DATABASE_TABLE_CREATION = "CREATE TABLE "+ UtilConstants.TABLE_NAME+"(" + UtilConstants.KEY_ID
        + " Integer PRIMARY KEY," + UtilConstants.KEY_NAME + " TEXT," +
        UtilConstants.KEY_PHONENUMBER + "TEXT" +  ")";
db.execSQL(DATABASE_TABLE_CREATION);

you are just going to create a SQL query.

Now imagine if you don't put a space after table the query will be something like this

CREATE TABLEsomeTableName ...... 

where someTableName is table name then it will cause an error because it is not a SQL query at all

Note: you don't have to mention space after table If UtilConstants.KEY_NAME contains space at the beginning that also works...

Answer 2

The SQL command would be CREATE TABLE [name]
You need the distance to produce the space, if you would not use the distance the command would be CREATE TABLE[name] it would detect it as two words
For example, you have in String DATABASE_TABLE_CREATION a space between String and DATABASE_TABLE_CREATION it would not work if you remove the space

Answer 3

Its because if you don't have the space " " character after these keyword like TABLE , the sql command will understand your keyword like TABLE[your_table_name] and that is not a valid SQL term.