blob

创建源

Conversely, to store BLOb data in a database, use the blob function.

方法

语法

返回

描述

The blobImage method fetches a BLOb from the database, creates a temporary file (in memory) of the specified format, and generates an HTML image tag that refers to the temporary file. The JavaScript runtime engine removes the temporary file after the page is generated and sent to the client.

While creating the page, the runtime engine keeps the binary data that blobImage fetches from the database in active memory, so requests that fetch a large amount of data can exceed dynamic memory on the server. Generally it is good practice to limit the number of rows retrieved at one time using blobImage to stay within the server's dynamic memory limits.

示例

cursor = connobj.cursor("SELECT NAME, THUMB FROM FISHTBL WHERE ID=2")
write(cursor.name + " ")
write(cursor.thumb.blobImage("gif"))
write("<BR>")
cursor.close() These statements produce this HTML:

Anthia <IMG SRC="LIVEWIRE_TEMP11"><BR> 示例 2. The following example creates a cursor from the rockStarBios 表 and uses blobImage to display an image retrieved from the photos column:

cursor = database.cursor("SELECT * FROM rockStarBios
   WHERE starID = 23")
while(cursor.next()) {
   write(cursor.photos.blobImage("gif", "Picture", "left",
      30, 30, 0,false))
}
cursor.close() This example displays an image as if it were created by the following HTML:

<IMG SRC="livewire_temp.gif" ALT="Picture" ALIGN=LEFT
   WIDTH=30 HEIGHT=30 BORDER=0> The livewire_temp.gif file in this example is the file in which the rockStarBios 表 stores the BLOb data.

blobLink

语法

返回

描述

The blobLink method fetches BLOb data from the database, creates a temporary file in memory, and generates a hypertext link to the temporary file. The JavaScript runtime engine on the server removes the temporary files that blobLink creates after the user clicks the link or sixty seconds after the request has been processed.

The runtime engine keeps the binary data that blobLink fetches from the database in active memory, so requests that fetch a large amount of data can exceed dynamic memory on the server. Generally it is good practice to limit the number of rows retrieved at one time using blobLink to stay within the server's dynamic memory limits.

示例

cursor = connobj.cursor("SELECT NAME, PICTURE FROM FISHTBL WHERE ID=2")
write(cursor.name + " ")
write(cursor.picture.blobLink("image/gif", "Link" + cursor.id))
write("<BR>")
cursor.close() These statements produce this HTML:

Anthia <A HREF="LIVEWIRE_TEMP2">Link2</A><BR> 示例 2. The following example creates a cursor from the rockStarBios 表 and uses blobLink to create links to images retrieved from the photos column:

write("Click a link to display an image:<P>")
cursor = database.cursor("select * from rockStarBios")
while(cursor.next()) {
   write(cursor.photos.blobLink("image/gif", "Image " + cursor.id))
   write("<BR>")
}
cursor.close() This example generates the following HTML:

Click a link to display an image:<P>
<A HREF="LIVEWIRE_TEMP1">Image 1</A><BR>
<A HREF="LIVEWIRE_TEMP2">Image 2</A><BR>
<A HREF="LIVEWIRE_TEMP3">Image 3</A><BR>
<A HREF="LIVEWIRE_TEMP4">Image 4</A><BR> The LIVEWIRE_TEMP files in this example are temporary files created in memory by the blobLink method.