private static final String CREATE_TABLE="create table course" +"(" +"cNumber varchar(10) Primary Key," +"cName varchar(10)," +"cClass varchar(10)," +"cTeacher varchar(10)," +"cTerm varchar(20)"+ ")"; private static final String CREATE_TABLE2="create table student_course" +"(" +"scNumber varchar(10) Primary Key," +"cNumber varchar(10) Foreign Key references course(cNumber)," +"cName varchar(10) Foreign Key references course(cName)," +"cClass varchar(10) Foreign Key references course(cClass)," +"cTeacher varchar(10) Foreign Key references course(cTeacher)," +"cTerm varchar(20) Foreign Key references course(cTerm),"+ ")";哪错了
时间: 2024-01-19 17:01:58 浏览: 39
在第二个表的创建语句中,最后一个字段有一个多余的逗号,应该删除它,正确的语句如下:
```
private static final String CREATE_TABLE2="create table student_course"
+"("
+"scNumber varchar(10) Primary Key,"
+"cNumber varchar(10) Foreign Key references course(cNumber),"
+"cName varchar(10) Foreign Key references course(cName),"
+"cClass varchar(10) Foreign Key references course(cClass),"
+"cTeacher varchar(10) Foreign Key references course(cTeacher),"
+"cTerm varchar(20) Foreign Key references course(cTerm)"
+")";
```
相关问题
public static final String DATABASE_NAME = "dict.db"; public static final int DATABASE_VERSION = 1; public static final String TABLE_NAME = "my_table"; public static final String DATA = "data"; public static final String WORD1 = "1"; public static final String WORD2 = "2"; public static final String WORD3 = "3"; public static final String WORD4 = "4"; public static final String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME + " (" + DATA + " VARCHAR(20)," + WORD1 + " INTEGER, " + WORD2 + " INTEGER, " + WORD3 + " INTEGER, " + WORD4 + " INTEGER);" ;哪里有问题
这段代码是用于定义数据库和表格的,目前没有明显的错误,但是可以提出一些改进的建议:
1. 数据库版本号可以考虑设置为更高的值,以便在后续的数据库升级时使用。
2. 数据库中的字段命名可以更加清晰易懂,比如可以将WORD1,WORD2等改成更有意义的名称。
3. 在CREATE_TABLE语句中定义字段的类型时,可以使用INTEGER、TEXT等更加明确的类型,以便在使用时更加准确。
private static final String CREATE_TABLE2="create table student_course" +"(" +"scNumber varchar(10) Primary Key," +"cNumber varchar(10) Foreign Key references course(cNumber)," +"cName varchar(10) Foreign Key references course(cName)," +"cClass varchar(10) Foreign Key references course(cClass)," +"cTeacher varchar(10) Foreign Key references course(cTeacher)," +"cTerm varchar(20) Foreign Key references course(cTerm)"+ ")";这段代码cNumber那一行的Foreign Key中的Foreign显示为绿色字体,下方有红色波浪线,出现了')', <column constraint> or comma expected,got 'Foreign'错误
这个错误可能是因为在创建外键时,引用的表没有被完全定义。请确保在此之前已经定义了course表,并且其中的每个列都已经被定义为主键或唯一键。此外,外键约束应该在列定义的末尾添加,而不是在列之后。你可以尝试将外键约束移到列定义的末尾,例如:
```
create table student_course (
scNumber varchar(10) Primary Key,
cNumber varchar(10),
cName varchar(10),
cClass varchar(10),
cTeacher varchar(10),
cTerm varchar(20),
Foreign Key (cNumber) references course(cNumber),
Foreign Key (cName) references course(cName),
Foreign Key (cClass) references course(cClass),
Foreign Key (cTeacher) references course(cTeacher),
Foreign Key (cTerm) references course(cTerm)
);
```
这样应该可以解决你的问题。
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