linux shell substitute variable

I have list of tables in t.txt file, I need to substitute all the ${table} instance with the table name in t.txt file. the challenge here is after the single quote, the ${table} variable will not be substituted, like the following code, only the first ${table} will be substituted, the last two does not. How can I do this? Thanks.

for table in `cat t.txt`
do

curl -XPUT "http://localhost:9200/_river/${table}_river/_meta" -d '{
    "type" : "jdbc",
    "jdbc" : {
        "driver" : "oracle.jdbc.driver.OracleDriver",
        "url" : "jdbc:oracle:oci:@test",
        "user" : "test",
        "password" : "test",
        "sql" : "select * from ${table} where rownum<3"
    },
    "index" : {
        "index" : "database",
        "type" : "${table}"
    }
}' 

done

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