sqlDelete

sqlDelete(table, [where], [from])

table can be an in-memory table or a DFS table.

where (optional) is a metacode indicating the where condition.

from (optional) is metacode indicating the from clause, which supports specifying table joins using ej or lj.

Dynamically generate a metacode of the SQL delete statement. To execute the generated metacode, please use function eval.

Example 1. Delete the records in an in-memory table

t1=table(`A`B`C as symbol, 10 20 30 as x)
sqlDelete(t1, <symbol=`C>).eval()
t1;

Example 2. Delete the records in a DFS table

if(existsDatabase("dfs://db1")){
    dropDatabase("dfs://db1")
}

n=1000000
t=table(take(`A`B`C`D,n) as symbol, rand(10.0, n) as value)
db = database("dfs://db1", VALUE, `A`B`C`D)
Trades = db.createPartitionedTable(t, "Trades", "symbol")
Trades.append!(t)
select count(*) from Trades;

// output
1000000

Trades=loadTable("dfs://db1", "Trades")
sqlDelete(Trades, <symbol=`A>).eval()
select count(*) from Trades;

// output
750000

Example 3. Delete records using table joins. The following example deletes records from t2 that have a matching id in both t1 and t2, where the flag in t1 is equal to 1.

t1 = table(1..5 as id, [1,2,2,1,1] as flag)
t2 = table(3..7 as id, [100,200,100,150,100] as profit)
sqlDelete(table=t2, where=<flag=1>, from=<ej(t2,t1,`id)>).eval()
t2