Very very important information which will be used in JDBC

All the examples are taken in the context of book table, that we have created today,

like this,

create table book (id INT,topic varchar(30),author varchar(30),price float,publisher varchar(30),primary key(id));

note: this table is created inside the database named as books

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so,

in java application we can use values as well as variable names inside sql statements 

while using jdbc 

#### we can pass a value for sql statements inside two single quotes   

syntax for insert:

insert into tablename values('value-1','value-2','value-n');

example for insert,

insert into book values('1','c++','kanitkar','450.0','PHI');

syntax for update:

update tablename set column-name='value' where column-name='value';

example for update,

update book set price='400' where author='kanitkar';

syntax for delete:

delete from tablename where column-name='value';

example for delete,

delete from book where publisher='PHI';

syntax for select:

delete from tablename where column-name='value';

example for select,

select * from book where publisher='PHI';

#### we can also pass a variable name inside two single quotes using given syntax    

syntax to pass a variable name inside sql statement:

<single-quotes><double-quotes>+VariableName+<double-quotes><single-quotes>

example,

' " +VariableName+ " '

some examples to show how to pass variable names inside sql statement in java application

## lets have some variables

int bookId = 10;

String bookTopic = "PHP";

String bookAuthor =" Rakesh";

float bookPrice = 400.0;

String bookPublisher = "BPB";

## now pass variable names inside insert statement

insert into book values('"+bookId+"','"+bookTopic+"','"+bookAuthor+"','"+bookPrice+"','"+bookPublisher+"');

## now pass variable names inside update statement

update book set price='"+bookPrice+"' where topic='"+bookTopic+"';

## now pass the variable names inside delete statement

delete from book where publisher='"+bookPublisher+"';

## now pass the variable names inside select statement

select * from book where author='"+bookAuthor+"' and publisher='"+bookPublisher+"';

note:

1. the insert or update or delete statement should be used inside executeUpdate() method of Statement interface

fact: the executeUpdate() method returns number of records affected inside the table

2. the select statement should be used inside the executeQuery() method of Statement interface

fact: the executeQuery() method returns ResultSet, which stores the data of a table