dumping data from views in mysql - mysql

Question

i have a view and want to extract its data into a file that has create table statement as well data.
i know that mysqldump doesn't work on views.

Answer 1

Obviously, there isn't an automated way to generate the CREATE TABLE statement of a table that does not exist. So you basically have two options:
Create an actual table, dump it and remove it afterwards.
Write a lot of code to analyse the view and underlying tables and generate the appropriate SQL.
First option is not optimal at all but it's easy to implement:
CREATE TABLE my_table AS
SELECT *
FROM my_view
You can now dump the table with mysqldump. When you're done:
DROP TABLE my_table
Second option can be as optimal as you need but it can get pretty complicate and it depends a lot on your actual needs and tool availability. However, if performance is an issue you can combine both approaches in a quick and dirty trick:
CREATE TABLE my_table AS
SELECT *
FROM my_view
LIMIT 1;
SHOW CREATE TABLE my_table;
Now, you use your favourite language to read values from my_view and build the appropriate INSERT INTO code. Finally:
DROP TABLE my_table;
In any case, feel free to explain why you need to obtain SQL code from views and we may be able to find better solutions.

Answer 2

Use SELECT ... INTO OUTFILE to create a dump of the data.

Answer 3

I have written a bash function to export the "structure" and data of a VIEW without creating a full copy of the data. I tested it with MySQL 5.6 on a CentOS 7 server. It properly takes into account columns with JSON values and strings like "O'Mally", though you may need to tweak it further for other special cases.
For the sake of brevity, I did not make it robust in terms of error checks or anything else.
function export_data_from_view
{
local DB_HOST=$1
local SCHEMA=$2
local VIEW=$3
local TMP_TABLE_NAME="view_as_table_$RANDOM"
local SQL1="
create table $TMP_TABLE_NAME as
(select * from $VIEW where 1=0);
show create table $TMP_TABLE_NAME \G
"
# Create an empty table with the structure of all columns in the VIEW.
# Display the structure. Delete lines not needed.
local STRUCT=$(
mysql -h $DB_HOST -BANnq -e "$SQL1" $SCHEMA |
egrep -v "\*\*\*.* row \*\*\*|^${TMP_TABLE_NAME}$" |
sed "s/$TMP_TABLE_NAME/$VIEW/"
)
echo
echo "$STRUCT;"
echo
local SQL2="
select concat( 'quote( ', column_name, ' ),' )
from information_schema.columns
where table_schema = '$SCHEMA'
and table_name = '$VIEW'
order by ORDINAL_POSITION
"
local COL_LIST=$(mysql -h $DB_HOST -BANnq -e "$SQL2")
# Remove the last comma from COL_LIST.
local COL_LIST=${COL_LIST%,}
local SQL3="select $COL_LIST from $VIEW"
local INSERT_STR="insert into $VIEW values "
# Fix quoting issues to produce executeable INSERT statements.
# \x27 is the single quote.
# \x5C is the back slash.
mysql -h $DB_HOST -BANnq -e "$SQL3" $SCHEMA |
sed '
s/\t/,/g; # Change each TAB to a comma.
s/\x5C\x5C\x27/\x5C\x27/g; # Change each back-back-single-quote to a back-single-quote.
s/\x27NULL\x27/NULL/g; # Remove quotes from around real NULL values.
s/\x27\x27{/\x27{/g; # Remove extra quotes from the beginning of a JSON value.
s/}\x27\x27/}\x27/g; # Remove extra quotes from the end of a JSON value.
' |
awk -v insert="$INSERT_STR" '{print insert "( " $0 " );"}'
local SQL4="drop table if exists $TMP_TABLE_NAME"
mysql -h $DB_HOST -BANnq -e "$SQL4" $SCHEMA
echo
}